Crime Lab

The Biology Section is comprised of two interwoven disciplines responsible for analyses in forensic serology and forensic DNA analysis. Analysts in the Biology Section use advanced scientific processes to detect body fluids, to collect biological material for DNA analysis, and to interpret complex results. These types of forensic analyses can provide investigative leads, identify potential suspects, exonerate innocent individuals, and contribute to court proceedings

Forensic serology is concerned with the examination and identification of bodily fluids. Evidence items found at a crime scene may be submitted to locate possible biological stains. Highly trained analysts then use specialized chemical and microscopic tests to determine the type of biological material possibly present. Serological tests are used in the identification of biological stains such as blood, semen, or saliva. If the possible biological material for DNA testing is skin cells, serological testing is not conducted; however, collection still may occur and proceed directly to DNA processing.

Forensic DNA analysis is a rigorous step-wise process consisting of the extraction of DNA from biological material, quantitation of human and/or male DNA present, amplification of specific DNA markers, and the detection and interpretation of the DNA data. A complete forensic DNA profile is a result of the amplification of 21 short tandem repeats which can be used for comparison and provide statistical weight to associations made to the DNA evidence. DNA profiles used for comparison may include or exclude known individuals referenced in a case or be searched within the Combined DNA Index System (CODIS) database. CODIS can provide investigative leads for specific crimes and can also be used to link a series of cases.

The Chemistry Section is responsible for testing evidence in three different types of cases – controlled substances (drugs), blood alcohol analysis (DWI cases) and fire debris testing (arson). The Chemistry Section is staffed with four full-time chemists.

Suspected drug evidence is tested to determine if an illegal substance is present. The suspected drug items are carefully weighed and samples are taken for instrumental analysis. Analytical instruments such as the Gas Chromatograph Mass Spectrograph (GCMS) and Infrared Spectroscopy (IR) are used to identify a wide variety of drug evidence such as marijuana, heroin, cocaine, methamphetamine, prescription drugs and other controlled substances.

Blood samples from drivers who are suspected of driving while intoxicated can be tested to determine the amount of alcohol that is present in a person’s system. When a subject is unable to blow into the intoxilizer for breath alcohol analysis, tubes of blood are taken for lab analysis. Samples of blood are injected into the Gas Chromatograph and the resulting ethanol amount is recorded in grams per 100 milliliters. Levels of 0.08 or above are considered legally impaired. Results as high as 0.40 have been recorded.

When arson is suspected, investigators can collect debris from fires scenes in sealed cans to be analyzed by the chemist. The Crime Lab has the ability to test samples of carpet, clothing, wood and other types of evidence to determine whether or not an accelerant was present at the time of the fire. The extracted material is injected into the Gas Chromatograph Mass Spectrograph (GCMS) to identify the accelerant. 

The Latent Fingerprint Section is a full service, accredited latent print laboratory. The section is staffed by four fully trained analysts and one investigative technician. The section provides evidence processing and human identification services for the Charlotte Mecklenburg Police Department.

The analysts employ a variety of forensic, chemical, physical and digital techniques to develop, visualize, preserve and identify latent print friction ridge impressions from evidentiary surfaces. The section also provides field assistance to the Crime Scene and Search Division that involves complex chemical surface processing, and support services to some outside agencies.



The analysts also perform comparative analysis of latent print evidence for the purpose of human identification. Latent fingerprint identification assists with criminal investigations, postmortem identification of unknown deceased individuals, suspect identification and victim eliminations.

The section also operates two State Automated Fingerprint Identification system terminals and has access to the FBI IAFIS national fingerprint database. These systems are used to search unknown latent prints against millions of fingerprint records maintained by the North Carolina State Bureau of Investigation and the Federal Bureau of Investigation.

The Firearms & Toolmarks Section employs three firearm examiners and an IBIS technician. Services provided by this section include determining operability of various types of firearms, bullet and cartridge case comparisons, determining the type of firearm from which a bullet or cartridge case was fired, serial number restoration, gunshot residue examinations and range determinations, toolmark comparisons, and footwear & tire comparisons.

Each year, thousands of firearms are submitted to the Firearms & Toolmarks Section, the majority of which are test fired and checked for operability. The section maintains a reference collection of various firearms and ammunition that can be used to assist in the identification of firearms and fired ammunition evidence submitted from crime scenes.

An indoor water recovery tank and a bullet trap allow the analysts to fire a variety of firearms on site and collect discharged ammunition component specimens for comparison and IBIS entry. After ammunition components are collected, the firearm examiner uses a comparison microscope to look at two items simultaneously in an attempt to determine if they were fired by the same firearm. The IBIS, which stands for Integrated Ballistics Identification System, is part of a national database network (NIBIN – or National Integrated Ballistics Identification Network) that contains the images of evidence and test-fired cartridge cases. Each specimen that is entered into the IBIS is compared to other specimens in the United States in an effort to link incidents where this type of evidence is recovered from crime scenes.

The Questioned Document Examiner is responsible for conducting analysis on any document when there is a question about its origin or authenticity.

The QD Section typically conducts examinations of handwriting, handprinting, typewriting, inks and counterfeit items. Documents are also examined for evidence of indented writing, alterations and obliterations.

Specialized spectrographic instrumentation and computer enhancement is often used to examine the evidence documents. Evidence items typically submitted to the section include forged and/or altered checks, threatening letters and bank robbery notes.