Most lay people do not appreciate the fact that there is a differentiation of labor in the laboratory as well as in the criminal justice community.
Trace Evidence – Small things are analyzed usually requiring the use of a microscope to identify them or compare them to known samples. Trace evidence examiners have clean examination rooms, many different instruments, and good lighting to analyze a myriad of things such as: hairs, fibers, glass, soil, explosives, wood, headlights, gunshot residue, shoeprints, tire tracks, fire debris for ignitable liquids, and many other small particles. Two analysts handle about 250 cases per year.
Controlled Substances – When police arrest someone for the sale or possession of street drugs, or if drugs or paraphernalia are found at the scene of a death, they are submitted to us to determine if they are controlled substances. We receive about 11,000 submissions per year. Because of Hamilton County rapid indictment laws, the suspect gets his day in court within 10 days of the arrest. Therefore, our drug chemists average a turnaround time of 4 days and do up to 250 cases per analyst per month. They open the cases and prepare the samples in the laboratory for instrumental analysis. The most common instrument used in this laboratory is the gas chromatograph/mass spectrometer.
Toxicology – Toxicologists analyze body fluids and tissues such as blood, urine, and liver for alcohol, drugs, and other toxic substances. Most of their work comes from the morgue where they help the pathologists determine cause of death. They also perform testing on OVI (operator vehicle impaired), DFC (Drug Facilitated Crime), and other miscellaneous crime lab cases. Not only do they determine what type of drug is in a person, or how much drug is present, but if it might be a lethal level. Would this amount of drug in a living person been able to impair them or not when operating a motor vehicle or contributed to a sexual assault case? Since each drug has its own extraction process, precisely deciphering all this information takes time. Therefore, our toxicologists try to maintain a turnaround time of 20-25 days.
Forensic Biology / DNA - These analysts identify and analyze biological samples such as blood, semen, urine, and saliva in all kinds of cases including homicides, rapes, assaults, burglaries, and many other crimes. Most of their time and expertise involves extraction, preparation, amplification, and identification of DNA in separate laboratory rooms. The sensitivity of this process is so good that DNA can be found on an item that was simply touched by an individual. DNA can be linked from an individual to a scene and from one case to another using a local, State, and National database system called CODIS. Our DNA analysts typically complete about 100 cases per month and solve 25 cases per month with CODIS hits. The probability of an individual DNA profile matching one particular suspect can often be determined as 1 in 1 decillion when we only have 7 billion people on the planet.
Firearms – During an autopsy a bullet can be extracted from a body and given to the firearms examiner to compare to a known bullet fired from a suspect’s gun in our firing range on the first floor. A microscopic examination of the two bullets can determine if they were fired from the same gun. Our firearms examiners are extremely busy examining guns, bullets, and cartridge casings from all the shootings you hear about in the news. Besides comparisons they do function tests, gun predictions, serial number restorations, toolmark examinations, and enter cartridge cases in the NIBIN database which can link one case to another. Each examiner has their own office to darken or set the lighting correct for their microscopic examination. The statistical information elsewhere on this site will give a more detailed breakdown of the types of cases each section processes. Each discipline, or laboratory section, requires special skills, but much of the work revolves around chemical instrumentation such as chromatographs and spectrometers as well as optical and electron microscopes.
The analyst usually knows very little about the facts of the investigation and is merely providing an analytical service for the investigator. Each analyst prepares a written report which is returned to the investigator with the evidence. The police integrate this report with other findings of their investigation and present the information to the prosecutor's office for adjudication. The prosecutor or defense attorney can call the analyst to testify at trial if necessary. Analysts also spend time performing equipment maintenance, quality control, safety and administrative functions, reviewing scientific literature, dealing with phone and e-mail inquiries and training police. In general, crime laboratories are becoming more and more reliant on advanced technology using auto samplers and robotics. Analysts are encouraged to do research as time allows, present papers at scientific meetings, and publish work in scientific journals. Some of our analysts have been requested to speak all over the United States and several foreign countries.