93rd SEMI-ANNUAL SEMINAR (Spring 1999)
May 12-15, 1999
Oakland, California

Stephen P. Allen, Manassas, VA

Information will be presented to inform the audience about the federally funded National Center for Forensic Science at the University of Central Florida and its management of the new Technical Working Group for Fire and Explosives Examinations. The mission of the National Center for Forensic Science (NCFS) takes it into many areas of interest to the forensic community. Included in the many focus areas is an interest in conducting fundamental research to gain insights into the basic nature of fire and explosion reactions. Also of interest is providing the support needed for the development of standard protocols for arson and explosion debris analysis. Additionally, the NCFS is interested in promoting the use of electronic media to access and exchange forensic information and making educational opportunities available to practicing professionals and full-time students. Lastly, the center is interested in partnering with the forensic science, law enforcement and business communities to promote improvements in the forensic science community. To this end, the CCFS sponsored a symposium in August 1997 which brought together experts in the fields of arson and explosion debris analysis to assist in identifying problem areas. Additionally, the NCFS has been named to administrate the Technical Working Group for Fire and Explosives Examinations (TWGFEX). TWGFEX is the latest in a series of several working groups which have been formed in the forensic science community. Its advisory board is made up of members from the International Association of Bomb Technicians, the laboratories of the Bureau of Alcohol, Tobacco and Firearms, Texas Department of Public Safety, Colorado State Police, Orange County Sheriff's Office, California and Federal Bureau of Investigation to name but a few. Its committee chairs and members are from diverse state, local and federal laboratories around the United States. Recently, the TWGFEX commissioned a major laboratory survey for fire and explosives debris examiners. The results of this survey and other aspects of the NCFS will be discussed. To enhance the success of the National Center, presentations are being made to regional forensic science associations and other pertinent groups so that its mission may be promulgated.

Kevin Andera, Orange County Sheriff-Coroner Forensic Science Services; Hiram Evans, Catherine Wojcik, San Bernardino County Sheriff Scientific Investigations Division

Objective and Conclusion: The formulation, use, advantages and limitations of a new microcrystal reagent for the detection of Gamma Hydroxybutyrate (GHB) are described. Gamma-hydroxybutyrate (GHB) was recently made a Schedule II Controlled Substance in California, obligating criminalistics laboratories to provide conclusive identification of suspected samples. Unfortunately, the nature of the compound complicates this task. Problems such as impure samples, need for derivatization for chromatography, conversion of the sample to and from the precursor during analysis, and the extremely hygroscopic nature of the drug all make identification by instrumental techniques difficult. The authors have developed a microcrystal reagent that can overcome some of these problems. The reagent, a 1% w/v aqueous solution of cupric nitrate and silver nitrate (e.g. 0.1 gram of Cu (NO3)2 and 0.1 gram of AgNO3 in 10.0 mL of water), forms distinctive crystals with a solution of GHB in less than five minutes. The GHB crystals are easily distinguishable from crystals formed upon evaporation of the reagent. Furthermore, the reagent does not form crystals with the precursor Gamma Butyrolactone (GBL). The reagent will form crystals in aqueous GHB solutions of concentrations down to 2 mg/mL, and will work with mixtures of GHB and GBL after minimal cleanup with toluene. The reagent was tested for specificity against over 25 compounds, including commonly occurring controlled substances, controlled substances that may have a biological effect similar to GHB (e.g. barbiturates and flunitrazepam) and two isomers of GHB (Alpha- and Beta-Hydroxybutyrate). None of these tests resulted in crystals similar to those for GHB. Finally, the Silver/Copper Reagent was tested in a blind trial against ten unknowns. Two were correctly identified as GHB, one GHB sample was not identified as such, and none of the other samples were incorrectly identified as GHB. The one false negative was not on a pure standard, and may have been due to the presence of interfering ions in the solution causing precipitation of silver salts. Microcyrstal tests are a fast and reliable method for identifying suspected controlled substances. The addition of such a test for the identification of GHB will give laboratories greater flexibility in performing what can be a difficult analysis. The lack of false positives in the testing shows selectivity for GHB, avoiding the danger of misidentification. While there can be false negatives due to the various factors that affect microcrystal tests, the combination of this technique with instrumental data should allow for rapid and accurate identification of Gamma Hydroxybutyate.

Larry Blanton, D-ABC Los Angeles Police Department

Two Forensic DNA cases are compared and contrasted. The emphasis of the presentation will focus on how detectives and prosecutors approached each case from a forensic perspective and how this impacted the Crime Laboratory

Cassandra Calloway, MS and Rebecca Reynolds, Ph.D. Roche Molecular Systems

This paper provides a better understanding of heteroplasmy and the challenges of interpreting data from mtDNA analysis of tissues. Mitochondrial DNA (mtDNA) has proven to be a useful tool for forensic studies because of its high copy number, maternal inheritance and high degree of sequence variability between individuals. For these reasons, mtDNA analysis is currently used by specialized labs for identification of telogen hairs, missing person remains and has been proposed for the identification of mass disaster remains. It has been suggested that a number of tissue types from the same individual be investigated to verify an individual's mtDNA type is identical from tissue to tissue. This should be done prior to the routine use of mtDNA typing in cases of mass disaster. This investigation is important since there is evidence of heteroplasmy (more than 1 mtDNA sequences within an individual) in the normal population and since differences in the level of heteroplasmy across tissues has been observed in individuals with mtDNA diseases. The purpose of this study is to determine if an individual's mtDNA type differs across various tissue types, and if the frequency of heteroplasmy differs across tissue types and among age groups. In this study, an immobilized sequence specific oligonucleotide (SSO) probe system was used. It consisted of 16 SSO probes that detect sequence polymorphisms within 5 regions of the hypervariable region II (HVII). This was done in order to screen for heteroplasmy and type tissue samples (heart, brain, muscle and blood) from 43 individuals. Sequence and cloning analysis were conducted to confirm that the observed multiple sequences were attributable to heteroplasmy, and not contamination. The frequency of heteroplasmy differed across tissue types being higher in muscle, and across age groups. Heteroplasmy was detected by the strip typing system in 5 of the 43 individuals (11.6%) and was detected by sequencing the HVII region in 22 of the 43 individuals (51.2%). Results from statistical analysis suggest that heteroplasmy increases with age, which may pose interpretation challenges. The results from this study also suggest that heteroplasmy may occur at certain positions more frequently than others (heteroplasmic "hot spots"). In conclusion, since the mtDNA type was not found to be identical from tissue to tissue, the observations from this study should be considered if mtDNA typing is used for identification of remains from mass disaster.

Michael Cariola DNA Technologist (QC) Armed Forces DNA Identification Laboratory

In 1992, the Department of Defense (DoD) established a DNA Registry comprised of DNA Specimen Repository (is this now AFRSSIR?) and the Armed Forces DNA Identification Laboratory (AFDIL) for the specific purpose of human remains identification. The following year, the Assistant Secretary of Defense for Health Affairs issued guidelines for the collection of DNA specimens. Whole blood, either from venipuncture or fingerstick, is collected as a bloodstain on Schleicher & Schuell #903 filter paper. The bloodstain is air dried and stored in a vacuum-sealed foil barrier pouch. One bloodstain card is stored in the service member's medical records and the other bloodstain card is stored at -20C at the DNA Specimen Repository. In addition, an oral swab (buccal scrapings) is collected and stored in isopropanol at room temperature at the DNA Specimen Repository. From June 1992 to July 1997, approximately 1.890 million oral swabs were collected. To date, the Repository has received XXX DNA specimens and, on average, XXX specimens come into the Repository daily. All DNA specimens are to be stored for 75 years before being destroyed. AFDIL has recently completed a six-month (June 1998 through November 1998) evaluation comparing bloodstains from the Armed Forces Repository of Specimen Samples for the Identification of Remains (AFRSSIR) to their corresponding oral swab also housed at AFRSSIR. This evaluation was carried out in conjunction with AFDIL's regular Quality Control (QC) program of reference bloodstains stored at AFRSSIR in order to try and determine the frequency of collection errors at military collection sites. Over this time AFDIL processed an average of 327.5 specimens per month totaling approximately 2000 specimens. AFDIL's regular QC program entails the typing of 600 specimens over this same time period. Specimens were analyzed with PE-ABI AmpFlSTR Profiler Amplification Kit (9 STR loci and gender determination locus). An update of the DoD DNA Specimen Repository Quality Control Program and the conclusions drawn from this study will be presented in detail.

Raymond J. Davis

Accreditation and certification have brought many positive changes to the practice of Forensic Science. The most important changes, in this author's opinion, are those which provide confidence to the legal community in which we serve. Documentation, standardized procedures, Quality Assurance / Quality Control and training, to name a few, have increased the trust and reliance judges and lawyers are placing on our work. The greater the confidence we can inspire, the easier our lives will be on the witness stand. One of the elements that will certainly make our lives, if not our work, easier is the Crime Scene Notebook. This is an idea whose time has finally arrived. And if this idea has arrived without my knowledge, then the actual implementation of this idea deserves some credit. This comprehensive document that will allow any criminalist, crime scene investigator or detective to record every detail of a scene investigation without having to resort to a profusion of loose leaf material. Everything that needs to be documented will be contained within the notebook. This notebook contains a crime scene procedural checklist, prepared forms, pages designed to hold Polaroid or 35mm prints, note pages and specialized paper for recording scene dimensions. In addition, a specific type of paper is utilized that will stand up to inclement weather and the numbered pages can't be removed without tell tale signs of tearing. The Notebook will provide the investigator a convenient and timely way to document the crime scene. This notebook will make it easier to review the investigator's work because everything will be contained within the notebook. Te-Tech, Inc. (408) 745-1133, located in Sunnyvale, California, produces these notebooks. They can customize the notebook to our agency's specifications. Slides will be shown during the presentation demonstrating the features of the Crime Scene Notebook. I invite your comments and feedback.

Raymond Davis 4 Exeter Avenue San Carlos, CA 94070

This case illustrates the events in a homicide case pitting the testimony of the medical examiner against the testimony of the criminalist. The conflict arose as to the distance the shooter was standing from the victim at the time of the fatal shotgun blast. This distance was critical in assessing whether the suspect would be tried for manslaughter or second-degree murder. Because this conflict was not resolved prior to trial, the prosecutors along with the investigating officer were left with no choice but to believe the popular and well known medical examiner over a lowly criminalist. Facts and evidence will be presented to highlight the conflict and the resulting interpretations made by the medical examiner and the criminalist. This conflict was eventually resolved during the trial with the jury reaching a verdict within 5 minutes.

Christie T. Davis, Ph.D. Simon Ford, Ph.D. Lexigen Science & Law, San Francisco, CA

Independent review of the records of DNA testing (lab notes, autorads, test-strips etc.) offers the criminal defense attorney an alternative or supplement to re-testing by an independent laboratory. In cases where all the biological evidence was consumed in the initial testing, independent review may be the only feasible defense approach available. Over the past ten years we have reviewed over five hundred DNA cases. We have seen virtually every type of Forensic DNA technology and have reviewed casework from a wide range of US and overseas laboratories. In the course of conducting these reviews, we have often been struck by instances in which the effectiveness of DNA casework is undermined by easily avoidable technical shortcomings. In this presentation, it is our intention to discuss examples of shortcomings in (1) testing strategy, (2) documentation, (3) report writing, (4) disclosure of discovery and (5) presentation. We hope that discussion of these issues will offer practical assistance to DNA caseworkers, and may help minimize unnecessary challenges to their work.

Mavis Hendson, Martin Buoncristiani, and Steve Lee; California Department of Justice DNA Laboratory

Magnetic beads can be used to purify DNA from blood, and to differentially purify epithelial cell DNA and sperm DNA from mixtures of epithelial and sperm cells. This paper describes the use of Dynabeads to purify DNA from blood, and to differentially purify epithelial and sperm DNA from a mixture of epithelial and sperm cells. Dynabeads are uniform spheres coated with magnetic material (Fe2O3 and Fe3O4) which provides them with superparamagnetic properties. Each bead is coated with a thin polymer shell which encases the magnetic material and provides a defined surface for the adsorption of selected molecules. In this study we used Dynabeads which specifically bind DNA. Dynabeads provide a simple, rapid and economical method of isolating high molecular weight PCR-ready genomic DNA directly from crude materials including whole blood, cultured cells and various human tissues. The procedure involves two steps. First, DNA is released and adsorbed to the surface of the Dynabeads. The second step is the magnetic separation of the intact DNA/Dynabead complex from the other components in solution. The sample tube is inserted into a magnetic stand, and the DNA/Dynabead complex is attracted to the wall of the tube by the magnetic field. A series of washing steps are performed to remove any residual contaminants before the DNA is resuspended. Our results indicate that 400, 200, 100, and 40 ng of DNA can be purified from 10, 5, 2.5, and 1 ul of blood, respectively, using 1 Unit (200 ul) of Dynabeads. This represents approx. 100% recovery of DNA assuming an average of ~6X103 white blood cells per microliter blood. Approximately 40 ng of DNA was obtained when 200, 100, and 50 ul of Dynabeads were used to extract DNA from 1 ul of blood, whereas approx. 25 ng of DNA was obtained using 25 ul of Dynabeads. This is within the range of the binding capacity of Dynabeads as specified by the manufacturer (Dynal; 200-500 ng DNA/200 ul Dynabeads). Comparable electrophoretograms were obtained when Dynabead and phenol purified DNA were amplified using the AmpFlSTR Profiler Plus typing system (PE Applied Biosystems, Foster City, CA), and the amplification products resolved and detected using the ABI Prism 310 capillary electrophoresis instrument (PE Applied Biosystems). The breakage of disulfide bonds of sperm cells by DTT prior to Dynabead DNA extraction was required in order to yield any DNA. No DNA was isolated from sperm when Dynabead DNA extraction was performed without the addition of DTT. A higher concentration of DNA was purified if Dynabead DNA extraction was performed immediately after the addition of DTT to sperm than when DNA was incubated with DTT at room temperature for 2 hrs before Dynabead DNA extraction. The requirement of DTT to aid in the lysis of sperm cells provided a means for the differential purification of DNA from epithelial and sperm cells from a mixture. The addition of Dynabeads to an epithelial/sperm cell mixture resulted in the lysis of epithelial cells and adsorption of epithelial DNA to the magnetic beads. The remaining lysate contained unlysed sperm cells and epithelial cellular material that had not bound to the beads. The addition of DTT and Dynabeads to this lysate allowed the lysis of sperm cells, the adsorption of sperm DNA to the beads, and the purification of sperm DNA as a separate fraction from epithelial cell DNA. Epithelial (e) and sperm DNA fractions were analyzed using the AmpFlSTR Profiler Plus typing system (PE Applied Biosystems, Foster City, CA). Results indicated that the e cell DNA fraction was contaminated with sperm cell DNA (ratio 2:1 of e cell:sperm DNA). More importantly, the sperm DNA fraction consisted predominantly of sperm DNA (ratio 40:1 sperm:e cell DNA). Amplification was also performed on non-eluted DNA in the presence of Dynabeads. Signals were much higher than those of DNA eluted from the beads Further research is being conducted to improve the yield of DNA from sperm cells.

Officer Pam Hofsass San Francisco Police Department / Forensic Services Division

  1. Forensic Science Review
    1. Basic Unifying Principles:
      1. Locard's Principle of Transfer
      2. Divisible Matter Theory
    2. Application to Evidence
      1. Association
      2. Individualization
  2. The Crime Scene
    1. Who's on first?
    2. Communication and Teamwork
    3. Outdoor vs. Indoor scene
    4. Overall steps:
      1. Documentation
      2. Processing
      3. Collection
    5. Safety issues
  3. One example of Strategies for collection: Blood Evidence at the Crime Scene
    1. Approach the scene/evidence as a scientist
      1. Ask the right question:
        1. What is its significance?
        2. What tests will be done in lab?
    2. Assessment/Recognition/Evaluation (see above)
    3. Presumptive tests; field vs. Lab
    4. Strategize
      1. Documentation: rough sketch/diagram/measurements
      2. Photography: stills / video
      3. Note taking
    5. Evidence collection and preservation
      1. Proper labeling and packaging
      2. Storage
    6. Contamination issues: "DWS"
      1. Avoidable versus unavoidable
      2. Keep items separate
      3. Control of the scene will help prevent problems
    7. Health and safety issues
  4. Closing Remarks:
    1. No such thing as the "perfect" crime scene
    2. Network/share information C. Debrief

Keith Inman, California Department of Justice DNA Laboratory; Norah Rudin, Forensic DNA Consulting

The learning objective of this paper is to re-examine and propose substantive and organizational changes to the current paradigm of forensic science. Forensic science is an applied science based on the laws of physics and chemistry. Over time, a set of fundamental precepts has developed that apply specifically to a forensic analysis. Traditionally five concepts are articulated: transfer, identification, individualization, association of reference and evidence items, and reconstruction of a physical event. We suggest that an additional sixth precept, the idea that matter must divide before it can be transferred, is necessary to complete the paradigm. Divisible matter is particularly useful in describing physical match evidence. Additionally, we propose that the paradigm logically divides into scientific principles that govern the generation of evidence, and concepts that pertain to the recognition, analysis and interpretation of evidence. The principles of divisible matter and transfer pertain to the generation of evidence before and during the crime event; the processes of identification, association by classification and individualization, and reconstruction describe the practice of forensic science starting with the recognition of an item as evidence.

Donald T. Jones San Bernardino Sheriff's Department

If sufficient information is present in reverse-dot blot mixture results, interpretations may be possible (based on dot intensities) which allows the DNA profile determination for the minor contributor to a mixed sample. A recent homicide case involved the analysis of the victim's fingernail cuttings to determine if the assailant's DNA may be present. Twelve fingernail fragments were individually extracted and then typed via PCR amplification using the Perkin Elmer PM+DQA1 and the Perkin-Elmer D1S80 kit. Two of the twelve samples indicated DNA mixtures consistent with the victim and an additional source. Assuming the presence of the victim plus one other person and taking a conservative approach to the interpretation, the suspect was included as well as 1 in 950 Caucasians, 1 in 1400 Hispanics, and 1 in 610 Blacks. A closer look at the dot intensities in the PM+DQA1 results and the D1S80 band intensity differences for the two mixture samples suggested exact genotypes for each of the seven loci examined. This DNA profile for the second contributor also included the named suspect as well as 1 in 82 thousand Caucasians, 1 in 210 thousand Hispanics, and 1 in 200 thousand Blacks.

Mike Kellet San Bernardino County Sheriff's Crime Lab

Many forensic examinations are comparative analyses. Comparisons are frequently done in an attempt to determine if two objects came from a common origin. If the two objects have common properties, the conclusion is they (did) or (may have) come from a common origin. The concepts of class, subclass and individualizing characteristics are used by forensic scientists to evaluate the "uniqueness" of a particular object. In some cases this evaluation is straightforward and follows standard professional practices. In other cases, the evaluation is not straightforward. Several types of physical evidence (bare footprint, blood/semen, shoeprints and tobacco) are evaluated in this presentation.

Gregory E. Laskowski, B.Sc., MPA Kern County District Attorney Forensic Science Division

Evidence recovered in a Kern County homicide investigation included a corroded partial pistol barrel, a partially charred carbide cutting wheel and various charred items from a burn site. Also recovered, were a spent .25 caliber TMJ bullet from the victim, a spent .25 caliber cartridge casing from a second burn site, a damaged Raven model MP-25 semiautomatic pistol from an abandoned water well, two spent .25 caliber TMJ bullets from the carcass of the suspect's dog, and an empty holster from the suspect's residence. The bullet from the victim, the holster from the suspect's residence, and the partial pistol barrel from the burn site were important pieces of evidence that revealed what the murder weapon was. X-ray analysis, Mikrosil casting, general rifling characteristic (GRC) databases, firearms reference collections, in addition to digital imaging and microscopic analyses were the tools and resources used to investigate this case. The firearm in question or its remaining components were never recovered, yet the type, make and model were clearly identified as a result of this investigation. The processes will be described.

Ira J. Rimson, P.E. Director, Forensic Investigations Veridata, Ltd. Albuquerque, NM

(Workshop Sponsored by the Virginia and A. Reed McLaughlin Endowment)

Outcomes of many current legal activities depend on successfully applied scientific principles during investigation and analysis. Scientific data and their interpretations by "experts" take on preeminent roles in both criminal and civil litigation. Yet few attorneys, and fewer forensic scientists, take the time to examine the diametric opposition between the basic concepts, which form the foundations of both law and science. This workshop will explore the conceptual and operational differences that cause cultural conflicts between attorneys and forensic scientists, and suggest methods for improving their mutual understanding and cooperation. Attendees will examine both traditional and innovative concepts of criminal and accident investigation and the effects of "conventional wisdom" on attorneys' and investigators' mindsets. Changes to the Federal Rules, both of Evidence and Civil Procedure, following the U.S. Supreme Court's Daubert ruling have led courts to deal more deliberately with scientific knowledge. Attendees will learn methods for evaluating the quality of their work processes and products, validating evidentiary relevance, and evaluating analytical logic as their investigation progresses, enabling them to avoid the unverified investigation data and unsubstantiated "expert" opinions which frequently lead to charges of "junk science" and "Hired Gun" experts, and implausible legal arguments. Attendees are invited to bring perplexing investigation data problems for use as examples in the practical section of the workshop.

Norah Rudin, Forensic DNA Consulting; Keith Inman, California Department of Justice DNA Laboratory

The purpose of this paper is to understand the evolution of concepts that has brought the profession of forensic science to its present state. As with any endeavor, it is useful to study the lessons of the past so that one can at least make new mistakes rather than recycle the old ones. We identify the roots of forensic science, trace some of the history, and highlight the evolution of concepts as well as practice. We hope that a brief reflection on the past will prove useful in guiding the future course of forensic science. A comprehensive Timeline of Forensic Science will be distributed. In the following presentation, The Origins of Evidence, we re-examine the current forensic paradigm.

Norah Rudin, Forensic DNA Consulting

The profession of forensic science has only recently (in the last decade) begun to define minimal expectations for laboratories and criminalists, the compliance to which is still largely voluntary. One of those expectations is for internal technical and administrative review of a case, before it is released from the laboratory as a signed report. Even in the best lab, the most competent criminalist may make an analytical or judgmental error that may slip by a harried supervisor. In the worst cases, malicious intent or incompetent analysis my completely invalidate a work product. It is the obligation of opposing counsel to retain a qualified expert to review the report, including supporting notes and data, to determine, 1) if the right question was asked, 2) if the data support the conclusions, 3) if any egregious errors occurred in any aspect of the collection, preservation, analysis, or interpretation. A detailed framework for review will be presented and particular points illustrated by case examples.

Faye Springer, Sacramento County Forensic Services Laboratory

A crime scene contains a wealth of information about how and why a crime occurred. This information must be recognized at the time the scene is processed for physical evidence, or it will be lost forever. Not only can the information be lost, but the investigators will never know it even existed. This presentation will describe a crime scene scenario with an emphasis in recognition of reconstruction evidence. At noon on a Thursday, the Riverside Fire Department received a call from a neighbor reporting a house fire. The house was totally engulfed in flames by the time the fire department arrived. When they entered the house, the fire department discovered three bodies in three different rooms. The Riverside Police Department was notified, and an investigation into a possible homicide/arson began. This presentation will walk the audience through the crime scene and will analyze the reconstructive significance of the different items of evidence. The audience will then be asked whether this crime is a double homicide/ suicide or a triple homicide.

Jane M. Taupin, Victoria Forensic Science Centre Victoria Police, Forensic Drive Macleod, 3085 Australia

Two celebrated Australian murder cases in the past two decades - the Chamberlain convictions and the conviction of Edward Splatt - have highlighted the serious problems that may exist when courts are faced with complex scientific evidence. These cases possessed distinctive features which attracted media attention that precipitated two Royal Commissions. Baby Azaria disappeared from a campsite in central Australia and her body was never found. Her mother was convicted of her murder, although she protested that a dingo had taken her baby. The presence of blood in the Chamberlain's car and the damage to Azaria's jumpsuit were two of the central forensic issues at two inquests, a trial and the Royal Commission. Major flaws in the original scientific evidence were uncovered during the Commission of Inquiry and the Northern Territory Government finally pardoned the Chamberlains. The Victoria Forensic Science Centre was the agent for the Royal Commission of Inquiry into the Chamberlain convictions and thus was faced with the problem of reevaluation of forensic evidence. Some of the particular problems encountered will be discussed, and how the need for experimentation rather than reliance on theory was clearly demonstrated. Edward Splatt was convicted of the sexual mutilation and murder of a 77-year-old widow in South Australia. A Royal Commission was held some seven years later where the forensic evidence was extensively debated. The evidence relied predominantly on the presence of paint, fibers and metal in the widow's home which allegedly could be traced to the accused. Again, serious problems concerning this evidence were revealed during the Commission of Inquiry and Splatt was pardoned. A failure to recognize the limitations of the forensic evidence and a propensity to fit the evidence to an alleged scenario occurred during both original trials. Whilst the initial impact on the popular perception of forensic science was negative, there was a lasting positive impact on the discipline that resulted from these reviews.

Mark Traughber, CA Department of Justice, Riverside; Terry Spear, California Criminalistics Institute, CA Department of Justice

The objective of this paper is to show an appreciation of the value of biological evidence collected in a suspect examination. In this paper, microscopy and DNA typing demonstrate the presence of female cellular material on penile and scrotum swabs. In sexual assault cases involving male suspects, finding victim's DNA types on penile swabs can be used to provide evidence of recent sexual activity. Given that semen is not found in a significant number of sexual assault cases, this evidence may be the only biological evidence linking a suspect and victim. In cases where the suspect wore a condom, the swabbed areas of the penis may not contain cellular material from the victim. This study looked at the feasibility of detecting cellular material (from the female partner) on the scrotum after coitus. In this study, the male volunteers were asked to take both penile and scrotum swabs following coitus. All of the samples collected were taken within a 15-hour period after coitus. These samples were then microscopically evaluated and extracted for DNA. Microscopy showed the presence of epithelial cells in every sample (penile swab and scrotum swab). Glycongenated epithelia were seen in 11 of 13 penile swabs and 10 of 13 scrotum swabs. Sperm cells were less prevalent than epithelial cells and were seen on the penile swabs from only two volunteers. Sperm cells were observed on only one of the scrotum swabs. The swabs were then extracted for DNA using a Chelex procedure. Not surprisingly, less DNA was obtained from the scrotum swabs than from the penile swabs. The calculated amount of DNA obtained from these samples ranged from 7ng to 150 ng. The DNA obtained from these samples was then typed using the DQAlpha and AmpFlSTR Green 1 loci. Typing results were obtained from all 13 sets of samples (penile/ scrotum sample). In the vast majority of these samples, only the female partner's types were detected. When the male's type was present, it appeared only as a minor component of the mixture. These samples may prove to be valuable in the investigation of certain sexual assault cases.

Mark Traughber, CA Department of Justice, Riverside

The California Department of Justice field lab in Riverside is one of the few labs in the State which performs only conventional serology for forensic biology related cases. We have the option of sending casework out to other labs for the purpose of DNA work (San Bernardino and DOJ Berkeley). Several cases will be presented which will illustrate the obvious need for DNA analysis in order to answer questions asked of us by the Criminal Justice System.

Fred Tulleners, MA California Department of Justice, Sacramento, CA; David Stoney Ph.D McCrone Research Institute; James Hamiel, B.S. California Department of Justice Riverside Criminalistics Laboratory

This study compared the striae patterns left by six consecutively manufactured chisels and four chisels of the same size and brand chosen randomly (without respect to the sequence of manufacturing). These 3/4" wide wood chisels were obtained from Buck Brothers, Riverlin Works Chisels. Test marks were made in lead tape using a jig that held the chisels at a 30-degree angle. The marks were then indexed and compared. A one-centimeter length of each chisel mark was compared in the phased position, in five predetermined non-phased positions, and in one "best" non-phased position (as determined by the analyst). Indexed and non-indexed (mismatches) of chisel marks made from the same tool were compared in a like manner. A group of six student interns were used for the data collection. The criteria used for analysis required the analyst to: (1) count the total number of striae observed in each mark, (2) count all matching striae in each comparison and (3) count the number and length of any runs of consecutive matching striae. For example, data on a comparison of two tool marks consists of the stria count for each tool mark, the number of isolated (single) matching striae, the number consecutive pairs of matching striae, the number of consecutive triplets of matching striae, and so forth, conveniently designated as the events of 1X, 2X, 3X, etc. Data was collected from the phased (match) position of tool marks from four chisels. Among these tests, consecutively matching striae greater than 5X were routinely observed and multiple occurrences of 4X were commonly seen in one mark. From the match position, these marks from the same tool were also examined when offset to five different non-phase positions (shifted successively by 1 mm). Among these tests, no occurrences of 4X or greater were observed. Single occurrences of 3X (that is, one in the full 1 cm comparison area) were found occasionally, with multiple 3X occurrences showing up rarely. When the single subjectively "best" non-match position was selected (rather than placing marks at pre-specified, non-phase positions) the results were the same: no 4X occurrences, occasional single 3X occurrences and only rarely a pair of 3X occurrences. There was a significant increase in the number of I X and 2X occurrences in these best non-match positions. The subjective choice of best phasing position, at least among newly trained analysts, appears to be dominated by the overall number of matching lines, as indicated by the 1X and 2X occurrences, rather than by a greater number of 3X occurrences. Overall, the absence of any 4X or higher occurrences in the mismatched positions, along with their routine and multiple occurrence in properly phased corresponding tool marks, provides the foundation for the hypothesis: Chisel marks have an objective, measurable threshold that can be set, above which one can be certain that a given correspondence results from an association rather than at random. Association is taken to encompass circumstances where an individual tool is itself individualized to a mark, as well as circumstances where a less than individual association is made, as in the case of non-individual production methods resulting in tools that produce similar marks. The present hypothesis is that we can unambiguously differentiate random from associative correspondence. Study of the production methods and wear of the tool is necessary to determine the meaning of the association (between the extremes of class and individual). In the present work, with ground chisel surfaces, the production process would be expected to result in no greater similarity among successively manufactured chisels than among others of the same class. This leaves the random occurrence of matching lines as the mechanism causing the correspondence seen in known mismatches. Further studies were made on comparisons of marks from different chisels. Marks from six consecutively manufactured chisels were inter-compared at fixed, phase positions relative to the chisel blade dimensions, as well as in the best non-match position. No observations of 4X or above were seen in any of these 30 intercomparisons (each of which was repeated independently by five separate analyst). Marks from another four chisels of the same make and manufacture, chosen without respect to manufacturing order, were also compared and inter-compared in the above manner with the same qualitative results. These results strongly support the hypothesis that an objective threshold, based on consecutively matching striae, can be set such that there is a clear distinction between random and associative stria correspondence. This distinction was explicitly apparent, even with analysts of relatively little experience. It can be anticipated that more highly experienced examiners would be sensitive to the same visual data and be able to adapt it as necessary to other types of tool marks. Modeling of the occurrence of 1X, 2X and 3X events on nonmatching comparisons showed that it closely followed an exponential decay curve, providing a theoretical model, along with the empirical rules described above, that can serve as a foundation for future research. Keywords: Toolmarks, individuality, statistics

Kenton S. Wong San Mateo County Sheriff's Forensic Science Laboratory

This case involved the examination of bullets recovered from the body of a homicide victim. Examination of the bullets revealed the presence of shearing marks, which suggested that a silencer was used. Information concerning markings on bullets caused by silencers has been previously published in the AFTE Journal. Miller reported a case involving two silencers in which it was observed that one silencer sheared the bullets, resulting in identifiable striae, while another caused a distinctive groove from the shoulder to the nose of the bullets (1). Miller also reported a case involving the examination and identification of bullets to a specific firearm and silencer combination (2). The laboratory became involved in the investigation of two homicides, which were performed during the commission of two separate robberies. One of these involved the use of a firearm which, according to a witness, had a silencer attached to it at the time of firing. After a lengthy investigation, an arrest was made, but according to the suspect, the firearm was dismantled, the barrel broken off, and the pieces were subsequently discarded into the San Francisco Bay. Evidence originally recovered from the scene consisted of four expended Companhia Brasileira De Cartuchos (CBC) brand, caliber .25 AUTO cartridge casings and four fired caliber .25 AUTO bullets recovered from the body of the victim at autopsy. Several months prior to the arrest of the suspect, a no gun ID of the autopsy bullets revealed the suspect firearm to be one of several caliber .25 AUTO semi-automatic pistols, which included a Jennings Bryco J25. With the aid of the suspect, investigators recovered only the frame of the dismantled Jennings/Bryco brand, Model 25/J25 semiautomatic pistol from the San Francisco By, seven months after the murder took place. As such, no identification of the bullets recovered from the body of the victim could be performed. The suspect, who was an accomplished mechanic and machinist, provided a detailed description of the construction of the silencer to investigators during his confession of the two murders. The silencer was constructed of alternating steel washers and rubber baffles inserted into a piece of machined aluminum tubing approximately 8" long ad 3/4" in diameter. For more information about silencer deign, refer to the article by Hueske (3). Based on these plans, the Rangemaster of the San Mateo County Sheriff's Office was able to reconstruct the silencer for court display purposes (with appropriate ATF approval as well as California Department of Justice exemption for law enforcement personnel.) An identical Jennings brand Model J25, caliber .25 AUTO semi-automatic pistol was procured from the laboratory's Firearms Reference Collection for test firing, with and without the constructed silencer. Test fires with the silencer attached revealed the consistent presence of shearing marks which were surprisingly similar to those observed on two of four of the autopsy bullets recovered from the victim. Despite the suspect's recanting of his confession of making and using the silencer (which weighted heavily towards pre-meditation of the robberies and subsequent homicides. The circumstantial evidence of the presence of silencer shearing marks in combination with the testimony of the suspect's girlfriend that the suspect had indeed constructed and used a silencer similar to that of the reconstructed silencer was an integral part of the information which aided the jury in rendering a guilty verdict. This laboratory very rarely encounters firearms equipped with silencers. If fired bullets are recovered from a crime scene or victim and display consistency in damage, then the possibility of the use of a silencer or other accessory equipment should be considered.

Jennifer E. Zeppa Oregon State Police Forensic Sciences Division

The advantages and disadvantages of the "generalist" philosophy vs. the "specialist" philosophy have been debated for years in the forensic community, and it appears in forensic laboratories the "specialist" philosophy is gaining ground. The Oregon State Police Forensic Services Division is no different, and in the recent past has focused efforts on specializing both current and new personnel. However, specialization has come with a price. As increased specialization has occurred in the laboratory system, gaps in case management and customer service were recognized. To remedy this, the concept of the Primary Examiner was born. This individual is trained to have a basic knowledge of all forensic disciplines and in effect is a version of the "generalist." This presentation will describe how this "specialty" field of "generalists" was developed, what the duties and expectations of a Primary Examiner are (both technical and administrative), how a Primary Examiner is trained and how the concept has changed.