The Illinois State Police Division of Forensic Services oversees the third largest system of crime laboratories in the world. Seven forensic laboratories provide forensic services to all of the approximately 1,000 law enforcement agencies in Illinois and work about 400 cases a year for federal agencies. The laboratories in ISP's system, accredited by the ISO/IEC, are located in Carbondale, Chicago, Joliet, Morton, Rockford, Springfield, and the Fairview Heights area. The specialty areas are as follows:
Daily crime laboratory work takes place to establish the scientific truth about evidence for court. Most ISP forensic science work involves laboratory/bench work analysis. Forensic scientists in the ISP respond to crime scenes infrequently. Rather, daily, the ISP's forensic scientists: 1) think across disciplines, i.e., "What could chemistry and biology and physics and anatomy tell me about this evidence in this crime scene?" 2) make clear bench notes about work, as these may be introduced as evidence in court, and 3) communicate well with one another so they will be able to testify clearly and withstand challenge in court. In addition, forensic scientists regularly train law enforcement personnel in the proper recognition, collection and preservation of evidence. The day-to-day work of a forensic scientist in an ISP crime laboratory, while evidence item and case circumstances vary, include aspects of all of the above activity.
Forensic biologists utilize chemical, enzymatic, and microscopical techniques to identify biological samples (e.g., blood, semen, saliva) associated with criminal cases. The forensic biologist can compare DNA genetic markers in crime scene samples to the DNA markers identified in standards from individuals believed to be involved in the case. This type of analysis establishes whether or not a particular individual could be a donor of the biological stain(s) found at the crime scene.
The DNA technology currently in use is based on the amplification process called PCR (Polymerase Chain Reaction). The questioned DNA is extracted out of a stain, amplified to produce sufficient material to test, and then analyzed. The DNA markers tested for are included in a class of markers called STR's ( Short Tandem Repeats). Thirteen different markers are used which offer a very high discrimination potential. These same markers are used throughout the nation so that a computer based search system can be used.
A new and powerfully informative approach to tracking and identifying criminals has emerged with advances in DNA technology. Illinois enacted a law in 1989 requiring persons convicted of a sexual offense submit blood samples for DNA analysis. In 2002, this law was expanded to include all felony offenses. The DNA Indexing Section was established in the Springfield Forensic Science Laboratory to analyze the samples collected under these legislative mandates. DNA analysis is performed on these samples and the results are placed in a computer database which is part of the national DNA database, CODIS (COmbined DNA Index System), being coordinated by the Federal Bureau of Investigation. Previously convicted felons can now be identified as potential suspects using computer searches against this DNA database. These searches compare DNA patterns developed from forensic samples with the DNA types from offenders on file in the computer. This search is useful in identifying repeat offenders, and assisting in serial crime investigations.
Drug Chemistry is responsible for the analysis of exhibits suspected of containing controlled substances (drugs) and Cannabis (marijuana). This includes plant materials, tablets, capsules, powders, paraphernalia and residues, but does not include biological specimens. These are analyzed by the Toxicology section.
The amount of substance is determined using a balance. During analysis, a case is inventoried with careful notes being made at this and each step of the analysis. Several options are available for preliminary testing, including traditional wet chemistry methods such as spot tests, thin layer chromatography (TLC) and extraction, as well as instrumental techniques such as ultraviolet (UV) spectroscopy and gas chromatography (GC).
Confirmation of substances tentatively identified is achieved via infrared spectroscopy (IR) or mass spectrometry (MS). Microscopy is also available for examining case material. A report is issued naming any controlled substances identified. Testimony in court is sometimes required to defend and describe the methods used by the forensic chemist or the conclusions that were reached.
Firearms identification, in its most basic form, determines whether or not an evidence bullet was fired from a suspect weapon. The forensic scientist may also be asked to compare fired cartridge cases, perform firearm function tests, serial number restorations and muzzle-to-garment distance determinations. Distance determinations utilize microscopic and chemical tests to identify gunpowder residues to determine the distance from which a shot was fired.
Toolmarks left at a crime scene by various types of tools (i.e., screwdrivers, pry bars, pliers) can be microscopically compared to test marks made in the laboratory by suspect tools. The forensic scientist is then able to positively identify or eliminate those tools.
Latent print identification is one of the oldest forensic sciences and was first used over 140 years ago. Latent print examination applies the principles of fingerprint examination to the unknown fingerprint deposits which are recovered from a crime scene or developed on objects submitted to the laboratory for fingerprint processing.
Fingerprint deposits are usually not visible to the naked eye due to the nature of their composition and the various types of surfaces upon which they are placed. Examiners attain the ability to visualize these deposits using a vast array of procedures, such as the application of powders, chemicals, fumes and dyes. Special devices, including powerful ultraviolet lamps and lasers, may also be utilized, as is photography and digital image enhancement. Ongoing research and development have introduced new procedures, such as liquid and vacuum metal deposition, into the laboratory.
Latent print examiners also acquire the specialized knowledge and skill necessary to individualize the one person who is responsible for a fingerprint deposit. The visualized, unknown latent print is analyzed to determine if sufficient information is present for a comparison to the inked fingerprint of a known suspect. Latent prints may also be searched in the Automated Fingerprint Identification System (AFIS), which contains the fingerprints of millions of persons, when a suspect is unknown.
Microscopists are specialists who routinely deal with pieces of physical evidence involved in criminal investigations. They are specially trained to patiently examine and compare various types of microscopic material to determine if there is a possible association to the crime under investigation. Although examinations primarily involve hairs and fibers, the Microscopy section also examines wood, building materials, safe insulation, fabric impressions and a broad group of miscellaneous materials called particulate unknowns
Instruments utilized by the Microscopy section include: stereo binocular microscopes which allow a low magnification with three-dimensional view; polarized compound microscopes which give a high magnification view used to identify many materials based upon microscopic appearance and optical properties; and comparison microscopes used to view two different specimens at the same time. Scanning electron microscopes, FTIR and computerized equipment are also available to perform special examinations.
Frauds, fabrications, and forgeries literally come under the microscope of examiners working in this section, which regularly scrutinizes handwriting, hand printing, typewriting, check writing, and printed materials for the purpose of identifying or eliminating an individual. Impression evidence including: rubber stamps, indented writing, glove impressions, and footwear and tire impressions also fall under the questioned documents section. The scope of examiners inquiries also take in any methods that may have been used to alter documents, such as eradication, obliteration, or paper alteration. Infrared and ultraviolet light, infrared luminescence, photography, laser and electrostatic enhancement of indented writing are among the special techniques used by examiners in this section.
Toxicology is the study of poisons. Forensic toxicology encompasses a broad spectrum of activity ranging from the isolation and detection of intoxicating substances in biological materials to providing expert testimony and interpretation of findings for police agencies and the judicial system.
The modern forensic Toxicology section utilizes a variety of analytical instrumentation and techniques to carry out its mission. Although the vast majority of analyses are performed using sophisticated, ultra sensitive electronic instruments, certain tests still require traditional chemical techniques for substance identification. Generally, the most difficult portion of any toxicology analysis is the process of isolating the toxic substance from the biological media. This must be accomplished in a manner that provides a concentrated sample which is relatively free of interference by naturally occurring substances. Once the compound is isolated, purified and concentrated, identification and quantitation become possible. In order to provide the user agency with sound information as to state of intoxication, degree of impairment or contribution to a fatality, the toxicologist must be informed as to the nature and circumstances of the intoxication as well as the quantity or concentration of the substance involved.
The Trace Chemistry section of the laboratory analyzes a wide variety of evidence types. Fire debris is analyzed for the presence of an ignitable liquid which may have been used as an accelerant in an arson fire. Debris from an explosion or a fragment of an explosive device is analyzed to identify which type of explosive might have been used. Paint and glass from a hit-and-run accident or a burglary can be compared to see if evidence left at the scene can be tied to a suspect.
Numerous other types of evidence are analyzed by the Trace Chemistry section. Quite often a comparison is performed between an unknown and a known substance to determine if they could have shared a common origin. Several analytical tools are utilized by the trace chemist. The stereo microscope is used for close visual examinations and for preliminary chemical spot testing. Analytical instruments are used to make comparisons and identifications. Some of the instrumentation used in the Trace Chemistry section includes gas chromatography, infrared spectroscopy, mass spectroscopy, x-ray diffraction, scanning electron microscopy and energy dispersive x-ray microanalysis.