Guide to Forensic Investigations: Trace Evidence, Ballistics, Toxicology, and DNA

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Reflecting on how forensic evidence is portrayed in the popular TV show “Making of a Murderer,” Vulture (2016) argues that the “CSI Effect” is alive and well. This term dates from 2008 and in recent years, the consequence of having ubiquitous crime dramas on TV has been two-fold: not only is the public increasingly interested in forensics, but real juries also are exhibiting unrealistic expectations about the collection and analysis of evidence. In one telling case, a real juror complained that the prosecution hadn’t been thorough because “they didn’t even dust the lawn for fingerprints.”

One way to correct misunderstandings about what types of categorical forensic evidence can be collected is to fall back on authoritative sources such as the the National Institute of Justice (NIJ 2016). The NIJ distinguishes ten kinds of evidence in the forensic sciences, including four types which are the focus of this guide: trace evidence, impression & pattern evidence (related to ballistics), toxicology, and DNA. As the NIJ points out, evidence serves many functions in investigations such as tracing illegal substances, reconstructing crime scenarios, and correctly identifying remains. As the methods and technologies in this crucial discipline continue to evolve, there is a growing demand for qualified forensics professionals specializing in specific types of evidence.

In efforts to ensure the proper collection, analysis, and use of forensic evidence, the US Congress passed the Criminal Justice and Forensic Science Reform Act in 2011. Introduced by Senator Patrick Leahy, this law requires that employees of federally funded laboratories and agencies have proper credentialing in their fields, which meet established guidelines of didactic education and hands-on experience. 

This guide serves as an introduction to how to meet the standards set forth by the 2011 law, examining the bright career outlook in forensic science and related occupations, as well as accredited educational programs, professional certification, and top employers across four high-growth forensic science subfields: trace evidence, ballistics, toxicology, and DNA.

Career Outlook & Salary in Forensic Evidence Examination

For people trained in a subfield of forensic science, there’s a wealth of job titles such as trace evidence analyst, forensics ballistics expert, forensic toxicologist, and DNA analyst, to name a few. The Bureau of Labor Statistics (BLS)—a branch of the US Department of Labor—is the predominant source of employment data. While the BLS does not track these more specialized occupations, if does offer an overview of the generalist forensic science occupation.

According to the BLS (Dec. 2015), there will be a 27 percent increase in job openings for forensic science technicians nationwide between 2014 and 2024, a figure substantially more robust than the average growth projected for all occupations during that time (7 percent). The  expected addition of 3,800 jobs coupled with the excellent salary prospects in this field make it ripe with opportunity.

In fact, the BLS (May 2015) found that the 14,070 forensic science technicians had an annual average salary of $60,090, a figure 24.4 percent higher than the average salary for all occupations in the country at $48,320 (BLS May 2015). In more detailed terms, these forensics professionals had the following salary percentiles nationwide:

  • 10th percentile: $34,000
  • 25th percentile: $42,320
  • 50th percentile (median): $56,320
  • 75th percentile: $74,000
  • 90th percentile: $94,410

Not surprisingly, the top-employing states correlated roughly with population size (BLS May 2015):

  • California: 2,270 forensic science technicians employed
  • Florida: 1,480
  • Texas: 910
  • Arizona: 790
  • New York: 710

In a stroke of good fortune of the Golden State, California was both the top-employing and top-paying state in the nation. Here were the top-paying states for forensic science technicians (BLS May 2015):

  • California: $79,490 annual average salary
  • Nevada: $73,210
  • Illinois: $72,680
  • Connecticut: $72,550
  • Massachusetts: $70,800

Interestingly, the salary prospects for forensic science workers also tended to vary by source of data. Payscale (2016)—an aggregator of self-reported salaries—found the following annual wage percentiles among its 214 responding forensic scientists:

  • 10th percentile: $36,000
  • 25th percentile: $42,000
  • 50th percentile (median): $51,205
  • 75th percentile: $72,000
  • 90th percentile: $87,000

Finally, Payscale (July 2016) also explored the salary prospects of forensic scientists by levels of experience. As with other occupations, wages tended to increase with more years on the job:

  • Entry-level (0-5 years), 193 respondents: $48,000
  • Mid-career (5-10 years), 70 respondents: $57,000
  • Experienced (10-20 years), 49 respondents: $66,000
  • Late-career (20+ years), 20 respondents: $74,000

Trace Evidence

One of the main subfields of forensic science is trace evidence. The National Institute of Justice (NIJ 2016) designates several types of residues that may transfer between people, objects, or places. These particles are sometimes invisible to the naked eye and may include hair, pollen, plants, geological materials, gunpowder, wood, cosmetics, lubricants, polymers, clothing fibers, glass, paint chips, plastic fragments, and other types of micro-debris. Through scientific testing, trace evidence analysts may link a particular sample to a criminal perpetrator through comparison with a control sample (i.e., a “standard”). As of July 2016, the NIJ had provided over $29 million in research funds in this subfield of forensics.

The Washington State Patrol (WSP) Forensic Services Guide adds that trace evidence analysts—also referred to as “microanalysis specialists”—may be called upon to collect specimens at crime scenes with equipment such as electrostatic or gel lifters (for shoe impressions), dental stone (for casts of tire-marks and other impressions), latent dust lifts (for shoe impressions), vacuums (for hair or fiber collection), and gunshot residue (GSR) kits. Oblique lighting or the Amido Black reagent may also elucidate shoe impressions in blood. Finally, trace evidence analysts may analyze evidence with a variety of techniques, including:

  • Stereomicroscopy
  • Polarizing light microscopy (PLM)
  • Fourier transform infrared spectroscopy (FTIR)
  • X-ray fluorescence spectroscopy
  • Microspectrophotometry
  • Melting point determinations
  • Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS)
  • Cross-sectioning microchemical testing
  • Thin layer chromatography (TLC)
  • Raman spectroscopy
  • Gas chromatography/mass spectrometry (GS-MS)
  • Capillary-electrophoresis (CE)

Fortunately for people in this field, there’s a thriving professional association for support in this often difficult line of work. The American Society of Trace Evidence Examiners (ASTEE 2016) boasts over 400 members who are practitioners, educators, students, and researchers who share common goals: to facilitate the exchange of information and ideas, to promote high professional standards and ethics, and to encourage continued research into methods and technologies of trace evidence analysis. ASTEE also has a peer-reviewed journal of developments in this discipline: the Journal of the American Society of Trace Evidence Examiners (JASTEE).

Educational Programs for Trace Evidence Analysts

Florida International University (FIU) not only boasts the world-class Trace Evidence Analysis Facility (TEAF), but also has the International Forensic Research Institute. One of the standout IFRI programs is the bachelor of science (BS) in chemistry (or biology) with a forensic emphasis. This program is accredited by the Forensic Education Programs Accreditation Commission (FEPAC)—the foremost accreditation authority for forensics programs—and provides a variety of on-campus and web-based courses to hone students’ grasp of concepts such as forensic evidence and forensic biochemistry applications. Additionally, students participate in a forensic science internship at a local facility to apply their knowledge in a real-world context.

Another outstanding hybrid (i.e., on-campus and online) program is available through the Hooke College of Applied Science in a partnership with the National Institute of Justice (NIJ). This continuing education training is one of the country’s only programs to be approved by the American Board of Criminalistics (ABC), one of the main professional credentialing groups in forensics. More than 400 trace evidence examiners have been educated through the Hooke & NIJ partnership in methods of sample preparation, fiber identification, forensic paint identification & comparison, electron microscopy, light microscopy, microspectroscopy, and more.

Trace Evidence Examiner Professional Certification

The American Board of Criminalistics (ABC) offers professional credentialing in criminalistics at the affiliate, diplomate, and fellow levels. These credentials are valid for five years. ABC has several subspecialities that may be relevant to trace examiners, including comprehensive criminalistics, fire debris analysis, hairs & fibers, and paints & polymers. To learn more about how to become professionally certified, please visit the forensic scientist careers page.

Top Employers of Trace Evidence Examiners

The American Chemical Society (ACS 2016) reports that 90 percent of forensic chemists—a field intimately related to trace evidence analysis—work in labs affiliated with local, state, or federal police departments and medical examiner offices.  

For example, the North Carolina Department of Justice has a full-service laboratory in Raleigh as well as satellite branches in Asheville and Greensboro. The North Carolina State Crime Laboratory is accredited under the International Organization for Standardization (ISO/IEC 17025 standards), and provides the full gamut of trace evidence analysis services with state-of-the-art equipment and techniques. Please note that similar to many crime labs across the nation, the NC DoJ also has summer internship opportunities in forensics.

Perhaps the most prestigious employer of trace evidence examiners is the Federal Bureau of Investigations (FBI 2016). Its Trace Evidence Unit (TEU) comprises a physical scientist, a geologist, and a team of forensic examiners who maintain a collection of reference samples as a basis of comparison for evidence submitted. Finally, the FBI Lab is one of the only ones in the nation to have a Mineralogy Group, a specialized unit of trace evidence geology experts.


In a summary of statistics about firearm usage and violence in the US, the BBC (Jan. 2016) reported that there were 372 mass shootings and 64 school shootings in 2015. Approximately 13,286 Americans were killed by guns that same year. Most alarmingly, the American gun-related death toll between 1968 and 2011 (1.4 million deaths) has overtaken the death toll from all US conflicts from the Revolutionary War through the War in Iraq (1.2 million deaths). The BBC estimated that there are approximately 300 million guns in the US owned by a third of the population, one factor that is contributing to the continued need for ballistics experts in the country.

According to the Washington State Patrol (WSP) Forensic Services Guide, there is a range of methods to determine relevant information about the type of firearms and bullet trajectories such as test-firing weapons, comparing cartridge cases, processing chemicals from gunshot residues (e.g., employing the sodium rhodizonate test), and using various techniques to elucidate obscured serial numbers on firearms (e.g., acid-etching, polishing). Interestingly, if firearms are fired at close range, the target surface is typically covered with partially burned and unburned gunpowder as well as soot and vaporous lead. It may leave a star-shaped or splintered bullet-hole with a darkened outline in its target, as opposed to a “cleaner entry” fired at longer range. One method law enforcement personnel use to identify the origin of bullets is through the National Integrated Ballistic Information Network (NIBIN), a database of firearms-related images and data. Although some ballistics experts focus solely on guns, others may become firearm and toolmark specialists who are familiar with the gamut of impressions left by various types of projectiles and blunt force objects.

Educational Programs for Ballistics Experts

Similar to other forensics subdisciplines, ballistics specialists typically complete bachelor’s programs in forensics or the natural sciences, and may focus their study with classes such as trigonometry, chemistry, computer-based modeling, and metallurgy. Others may learn exclusively on the job—particularly those employed in law enforcement—and garner skills such as handling evidence, identifying types of firearms, and acting as expert witnesses in court.

For those interested in formal educational training, there’s a joint associate and bachelor’s of science (AS/BS) degree available through a partnership between Queensborough Community College and the John Jay College of Criminal Justice. The AS portion focuses on foundational mathematics and science, and the BS portion has three distinct emphases: toxicology, molecular biology, and criminalistics. In the criminalistics concentration, students receive comprehensive training in ballistics, and graduates of this dual-program have gone on to work at local and state police laboratories, as well as at the FBI and the DEA.

For students who already have a bachelor’s degree and are interested in more advanced training, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) provides ballistics-specific education and certification through its National Firearms Examiner Academy (NFEA). As of July 2016, the NFEA is the sole national training program with a standardized curriculum in firearm forensics. It takes one year to complete and comprises 18 modules of instruction such as serial number restoration, toolmark identification & comparison, and a generalized NFEA course designed for state and local crime lab employees.

Ballistics Specialist Professional Certification

While there is no credentialing entity in this field recognized by the Forensic Specialties Accreditation Board (FSAB), the Association of Firearm and Tool Mark Examiners (AFTE) is an international group which provides a five-year certification. To qualify, candidates must have a bachelor’s degree, at least three years of experience as a firearm and/or toolmark examiner, and training equivalent to the two-year course of study in the AFTE Training Manual.

Top Employers of Ballistics & Firearms Experts

Firearms forensics experts go by many job titles—ballistics analysts, ballistics scientists, and firearms & toolmark examiners— and while most are employed through federal, state, and local crime labs, others may work at corporations such as American Systems. This employee-owned company was founded in 1975 and is focused on keeping members of the armed forces safe in challenging contexts around the world. As a government services contractor, it offers services of “National Priority,” including firearms and toolmark examination. In addition to test firing weapons, these specialists are tasked with analyzing evidence using magnification, etching, x-ray, and various photographic techniques to uncover the source of ballistics paraphernalia.

As with other subfields of forensics, one of the most prestigious employers of these forensics professionals is the Federal Bureau of Investigations (FBI 2016). The Firearms/Toolmarks Unit (FTU) supports law enforcement agencies nationwide by closely examining physical evidence from guns, ammunition, toolmarks, gunshot residue, and projectile trajectories. In the FTU, they employ varied techniques such as firearms function testing, trigger pull measurements, ejection pattern examination, silencer testing, and other advanced ballistics methods.

Forensic Toxicology

The National Institute of Justice (NIJ 2016) defines forensic toxicology as the scientific analysis of biological samples for toxins (e.g., pharmaceuticals, drugs & alcohol, poisons). As a continually evolving field, the collection methods and testing techniques are always in flux. Toxicology not only seeks to understand the effects of various substance concentrations, but also how drugs are distributed throughout the body. The aforementioned Washington State Patrol (WSP) Forensic Services Guide offers a detailed explanation of its State Toxicology Laboratory in Seattle. In many cases, the lab tests blood, urine, hair, or other types of tissues to assess whether drug or alcohol use contributed to a person’s criminal activity or death. In WA and many state police labs, there are four common types of cases submitted for toxicology testing: DUIs, death investigations (i.e., postmortem examinations), drug facilitated sexual assaults (DFSAs), and drug use inquiries.

Educational Programs for Forensic Toxicologists

Luckily for those interested in forensic toxicology, there is an abundance of focused college degrees in this field, including programs accredited by the prestigious Forensic Science Education Programs Accreditation Commission (FEPAC). For example, the West Chester University of Pennsylvania offers a bachelor of science (BS) in forensic and toxicological chemistry, focusing its training on professional laboratory experience with a foundation in forensic science. With advanced coursework in forensic chemistry, forensic microscopy, microbiology, and recombinative DNA techniques, West Chester graduates have successfully secured employment in crime labs throughout the country.

Additionally, George Washington University (GWU) of DC offers a FEPAC-accredited master of forensic science (MFS) in forensic toxicology. Open to students with bachelor’s degrees in chemistry or biology, this 36-credit graduate program includes classes such as criminal law for forensic scientists, principles of toxicology, medicinal chemistry I/II, statistics, and professional responsibility & quality assurance. Finally, GWU forensic toxicology students are encouraged to complete internships at one of the many local toxicology labs in the area. To learn more about relevant educational programs in this field, please visit the forensic chemistry programs page.

Forensic Toxicologist Professional Certification

The American Board of Forensic Toxicology (ABFT) provides three specialized categories of certification in this field: forensic toxicology, forensic alcohol toxicology, and forensic drug toxicology. All are valid for five years. To qualify, candidates must have at least a bachelor’s degree, three years of experience, and a passing score on an exam. To learn more about credentialing and how to join this career, please check out the how to become a forensic toxicologist page.

Top Employers for Forensic Toxicologists

There is a vibrant employment landscape for forensic toxicologists. In fact, the Society of Forensic Toxicologists, Inc. (SOFT) provides an active job-post board with opportunities at places such as Quest Diagnostics, Unitec Laboratories, PremierTox Laboratory, Captiva Lab LLC, Dynacare, and the DC Office of the Chief Medical Examiner. One standout position was available at the Houston Forensic Science Center, which called for a toxicology analyst to perform chemical analyses on biological samples and prepare reports to facilitate criminal justice proceedings. These specialists may also be called upon to testify in court as expert witnesses.

Additionally, the Virginia Department of Forensic Science’s central lab in Richmond employs forensic toxicologists for medical examiner cases, DUI investigations, non-implied consent examinations (e.g., drug-assisted sexual assault), and alcoholic beverage testing, particularly for minors caught in possession.

DNA Analysis

Perhaps one of the most groundbreaking innovations in the realm of forensic evidence has been the emergence of DNA analysis. Since the late 1980s, this field both has provided biological evidence connecting criminal perpetrators to victims or crime scenes, and also has exonerated those who were wrongly accused. The National Institute of Justice (NIJ 2016) states that one one-tenth of a percent of DNA—approximately three million base pairs—differ between individuals, and biological samples from blood, hair, semen, bone, saliva, and other tissues can be used for testing. The NIJ (May 2016) added that there’s an especially high demand for qualified DNA specialists since there’s a mounting backlog of samples which can make or break criminal cases across the country.

After a viable sample has been located and carefully collected, DNA and serology analysts employ techniques such as DNA typing (i.e., chemically removing DNA from cells), real time (RT) polymerase chain reactions (PCR), single nucleotide polymorphism (SNP) testing, or the Y short tandem repeat (Y-STR) procedure for male DNA. Once a sample is processed, it can be compared to known samples in Combined DNA Index System (CODIS) or National DNA Index System (NSIS) databanks.

Educational Programs for DNA Analysts

Many programs in forensic chemistry and biology provide in-depth training on DNA analysis. For example, the FEPAC-accredited bachelor of science (BS) in forensic chemistry at Towson University of Maryland offers three distinct tracks: general forensic science, trace evidence & drug analysis, and DNA. Boasting small class sizes, ample student-professor interactions, and abundant externship opportunities at local crime labs, Towson provides hands-on training in body fluid analysis and human identification using serology, DNA technologies, and elementary biostatistics.

Two additional FEPAC-accredited programs are available at Cedar Crest College of Allentown, PA: a BS and a master of science (MS) in forensic science. Both offer excellent training in forensic molecular biology, and the MS has specialized coursework in fluid stain identification, DNA extraction, DNA quantitation, PCR, and genotyping. Most notably, while this is the only women’s college in the nation to offer degrees in forensic science, chemistry, biochemistry, and genetic engineering, it also enrolls men at the graduate level. To learn more about relevant education in this field, please visit the forensic biology programs page.

DNA Analyst Professional Certification

The American Board of Criminalistics (ABC) offers professional credentialing in criminalistics with a specialization in molecular biology. To qualify, an aspiring DNA analyst must have a bachelor’s degree, at least two years of experience, and a passing score on an examination. To discover in-depth how to join this subfield of forensic evidence, please visit the DNA analyst career page.

Top Employers of DNA Analysts

Similar to the opportunities available through other branches of forensics, there are crime labs across the country which employ DNA experts. In fact, the Association of Forensic DNA Analysts and Administrators (AFDAA July 2016) posted openings in this field at the Alameda County Sheriff’s Office, the County of Los Angeles, the City of Fort Worth Police Department, and the State of New Mexico, to name a few. Furthermore, as with other forensic evidence subfields, the FBI boasts a specialized, state-of-the-art DNA Casework Unit, employing forensic examiners to identify body fluid stains and analyze DNA.

Other Types of Forensic Evidence & Resources

While this guide focuses exclusively on trace evidence, ballistics, toxicology, and DNA, there is a range of forensic evidence subfields. To learn more about any of these areas, please visit the pages below:

Finally, here is a list of additional authoritative resources for people interested in forensic science and investigations:

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Jocelyn Blore

Jocelyn Blore is the chief content officer of Sechel Ventures and the co-author of the Women Breaking Barriers series. She graduated summa cum laude from UC Berkeley and traveled the world for five years. She also worked as an addiction specialist for two years in San Francisco. She’s interested in how culture shapes individuals and systems within societies—one of the many themes she writes about in her blog, Blore’s Razor (Instagram: @bloresrazor). She has served as managing editor for several healthcare websites since 2015.