Criminalistics Information


A criminalist is a person with a background in science, typically having at least a baccalaureate degree in an area such as chemistry, biology, forensic science, or criminalistics. Some criminalists have degrees in other, similarly related areas. Many criminalists have advanced degrees.

With the above scientific background and additional training given by his/her employer (either a government or private laboratory) a criminalist applies scientific methods and techniques to examine and analyze evidentiary items and testifies in court as to his or her findings. Please read below, under criminalistics, for a more detailed description of what criminalists do.


The California Association of Criminalists (CAC) is a professional membership organization of forensic scientists founded in 1954 by sixteen members from various agencies throughout California. They met to exchange ideas, new testing methodologies and to share case histories. Since its inception, the CAC has expanded its membership throughout the United States and Europe. The CAC is the oldest established regional forensic science organization in America. CAC Members are employed in local, state and federal governmental agencies, as well as private companies and teaching institutions.

Today, there are many members representing an array of forensic science specialties. They include criminalists, document examiners, serologists, toxicologists, chemists, molecular biologists, firearm & toolmark examiners and educators. CAC members are involved in national forensic science organizations such as SWGDAM, SWGMAT, ASCLD, ASCLD-LAB, ASTM E-30, DAB, ABC and AAFS. CAC membership provides an opportunity to be involved in the professional activities that affect one's career, the profession of criminalistics and the criminal justice system.


Firearms and Toolmarks
Criminalists provide information to investigators about the caliber and type of firearm used in a crime. Scratches, or striation marks, are left on bullets by the barrel of a pistol or rifle. Once a firearm is recovered, these marks can individualize a bullet to a unique firearm to the exclusion of all other firearms. Similarly, tools used in crimes can leave striation and other marks on surfaces. These marks can be compared to the tool believed to have made them. If the comparison is a positive match, a tool may be individualized as having made the mark to the exclusion of all other tools. A computer database of marks on cartridge cases and bullets has been developed to link a particular firearm to serial crimes.

Trace Evidence
Trace evidence, frequently overlooked because of its microscopic size, applies microanalysis to fibers, hair, soil, paint, glass, pollen, explosives, gunshot residue, food, plastic bags, and virtually anything involved in a crime. No training exists that will prepare the trace evidence analyst for every kind of case that will cross their workbench, as each case is fascinatingly unique. By having a thorough knowledge of the advantages and disadvantages of microscopic, spectroscopic, and chromatographic methods, the criminalist can meet the analytical challenge of each case.

DNA and Serology
In the mid 1980s, deoxyribonucleic acid (DNA) techniques began to be applied to forensic cases. Any tissue from the body carrying the genetic code of DNA may be used to compare to a standard. This can possibly allow blood and other biological material to be associated with an individual. Databases of DNA profiles have been compiled to aid in identifying criminals and have been used to solve cases many years old, where samples were properly preserved and reanalyzed. In some cases innocent persons have even been released from prison based on the reanalysis of DNA evidence.

Drugs, Alcohol and Toxicology
The criminalist uses a battery of analytical tools and their knowledge of chemistry to identify controlled substances in powders, pills and liquids and body fluids. A criminalist may be called to a clandestine laboratory by investigators, where illegal drugs are produced. Criminalists are frequently responsible for maintaining breath alcohol analysis instruments and training of the laboratory technicians and police officers who run the tests on those suspected of driving under the influence. Sometimes no controlled substance is present and sometimes more than one kind of drug can be detected in a sample.


Criminalistics is one of many divisions in the field of forensic science. Forensic science includes forensic pathology, odontology, entomology, engineering, criminology, and other disciplines. All of these are specialized sections in forensic science. Criminalists use techniques learned in chemistry, molecular biology, geology, and other scientific disciplines to investigate and solve crimes. Criminalistics should not be confused with the field of criminology. Criminologists are sociologists, psychologists, and others who study the causes and effects of crime on society.

For the criminalist, crime scene investigation involves the recognition, documentation, collection, preservation, and interpretation of physical evidence which may be as big as a truck or as small as a diatom or pollen grain. Recognition of items out of place, articles improperly located or items added to the crime scene are an important part of crime scene processing. The criminalist collects, preserves, and makes interpretations about the evidence and their relation to the series of events resulting at the crime scene.

The criminalist brings evidence back to the laboratory where examinations will be conducted. Interpretations are made about the relevance of a particular item from the crime scene by associating particular items of evidence to specific sources and reconstructing the crime scene. This means not only associating a suspect with a scene but also the telling of a story about what transpired before, during and after the crime. The criminalist must draw on a wide spectrum of scientific knowledge including chemistry, biology, genetics, molecular biology, physics, statistics and a working knowledge of civil and criminal law. Applying this knowledge, criminalist will associate and identify evidence, interpret the results, reconstruct the crime scene, and write a report summarizing the findings.

Finally, the criminalist testifies in courts of law, teaching the judge and jury about the conclusions reached in the laboratory.


The end of the journey is the court room where testimony of the crime scene work, laboratory analysis, the conclusions on the report and interpretation of the evidence will be presented and questioned. The criminalist tells the truth in an unbiased manner, educating the jurors about the techniques that were used, the results obtained and interpretations derived from those conclusions. The criminalist must answer the question posed so that their answer is not misleading the jurors. If the question posed requires a yes or no answer but an explanation is needed to explain the yes or no answer, they are obligated to give an explanation. Professionally, the criminalist does not care whether the defendant is found guilty or not guilty. Presentation of the evidence in a fair and unbiased manner and telling the truth are the primary obligations of the criminalist.