Body of Evidence

From labs handling seized drugs to photos used in the courtroom, standards play a crucial role in forensic sciences.
Jack Maxwell

Fingerprints. A scrap of cloth. A blurry image from a surveillance video.

Sketchy, ephemeral clues like these are often the only leads authorities have when investigating a crime or accident. How data and objects are identified, analyzed, and interpreted can make the difference between justice achieved or justice denied.

The legal system relies on forensic science to deliver accurate, rigorous, and unbiased information on everything from gunshot residue to tire tread impressions, DNA matches to TNT batches. Since 1970, ASTM International’s committee on forensic sciences (E30) has worked to promote the “knowledge and development of standards (test methods, guides, practices, classifications, and terminology) for… definitions, methods, and standard reference materials for the collection, preservation, scientific examination, preparation, and reports relating to physical evidence for forensic purposes.”

From the Lab to the Morgue

Forensics professionals represent a wide variety of disciplines: chemistry, biology, geology, anthropology, dentistry, and more. Most have at least one thing in common: the need for scientifically sound standards.

Susan Hetzel relies on ASTM standards for analysis of fire debris. “There are four or five different ASTM methods on how to prepare or extract your residues from your debris,” notes Hetzel, main committee secretary and co-chairman of E30’s subcommittee on criminalistics (E30.01), and senior analytical chemist at S-E-A Ltd. These include solvent extraction, gas chromatography-mass spectrometry, and passive and dynamic headspace concentration. “There are different ways to get the residue out of the debris, so there are several different standards addressing that, and there’s one standard addressing the actual instrumental analysis of those extracts.”

New technologies like digital imaging also must rest on a foundation of robust, widely accepted standards. Richard Vorder Bruegge, a senior photographic technologist with the U.S. FBI (and E30’s chairman), points out that, despite the ubiquity of Photoshop, there are still courts that won’t allow digital modification of images. Hence the particular value of the guide for forensic digital image processing (E2825).

“A lot of judges want to see the evidence, and they are concerned that digital image processing manipulates the evidence in a way that may not be legitimate or valid,” he says. “So the fact that we have this standard guide for forensic digital image processing basically tells the court that this sort of processing is an accepted part of image analysis, image enhancement, video analysis. It provides a tool that allows lawyers to get digitally enhanced images admitted into court.”

Hetzel echoes this crucial point. “How many judges are forensic scientists? Not very many. What they know and what they don’t know is relatively limited, but if they know that these standards exist, they can start using that as a requirement for letting things in or not.”

Even more traditional forensic specialties, like postmortem photography, benefit from rigorous standards, especially when they interface with modern technology.

Lora Sims is a senior biometric examiner at Ideal Innovations Inc. and one of the newer members of Committee E30. She has been involved in the development of a new standard (WK57017) that will help forensic photographers.

“This standard is being generated to provide guidance to those who take postmortem images, to take the best images to search through a facial recognition system, and to be used for facial identification,” Sims says. The standard will include nuances such as the angle to shoot from, optimum distance between subject and camera, and how to prepare the face and capture profiles.

Committee E30 is working on a number of other projects, including ongoing revisions to the standard for terminology relating to forensic science (E1732). “Words matter,” Vorder Bruegge says. “And in court, words are all you’re dealing with for the most part. There’s physical evidence, but when you go into something like an appeal, cases that go up to the [U.S.] Supreme Court depend upon the written word, so it’s absolutely vital that the standards and the terminology used are clearly defined.”

Another key E30 initiative involves education. “It’s really important that the people that are doing this work in court have the right level of training and that they continue to improve,” says Vorder Bruegge, “and so we’re working on a guide for training and continuing education to make sure that forensic scientists will meet certain standards for what they need to know.”

Convergence of Efforts

Over the nearly five decades since its formation, E30 has played an important role in creating standards relevant to various branches of forensic science. Many are in use today, including practices for: evaluating scientific and technical data (E678), examining items involved in criminal or civil litigation (E860), and reporting opinions of scientific and technical experts (E620 — more on this one later).

For many years, scientific working groups (SWGs or “swigs”) linked to specific forensic science disciplines were also on the case. More than 20 “swigs” made important strides to identify best practices in areas like DNA and bloodstain pattern analysis, shoe print and tire tread evidence, firearms, tool marks, and facial identification.

But in 2009, a watershed report from the National Academy of Sciences, “Strengthening Forensic Science in the United States: A Path Forward,” was published. The report acknowledged the professionalism of those in the field, but it also leveled some pointed criticism that led to the creation, in 2014, of the Organization of Scientific Area Committees within the U.S. National Institute of Standards and Technology.

Most of the “swigs” were absorbed into OSAC and became subcommittees devoted to their particular area.
OSAC also began to maintain a registry of “technically sound, consensus-based, fit-for-purpose documentary standards that are based on sound scientific principles.” This registry currently contains eight standards, including three from ASTM International.

The “Mt. Rushmore” of Standards

The three ASTM standards on the OSAC registry are the practice for identification of seized drugs (E2329), the guide for sampling seized drugs for qualitative and quantitative analysis (E2548), and the test method for forensic comparison of glass using micro X-ray fluorescence spectrometry (E2926).

“The drug analysts developed E2329 to ensure that a valid, reliable analytical scheme is conducted, even though different laboratories may have different instrumentation,” says Barbara Andree, a forensic chemist with the U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives and chair of the subcommittee on interdisciplinary forensic science standards (E30.11). “The standard specifies minimum combinations of tests that need to be conducted, based upon the specificity of the particular examination(s).”

Standard E2329 holds a special distinction in the OSAC registry. Vorder Bruegge explains. “Basically, the purpose of OSAC in large part is to serve as the clearinghouse for the best of the best standards,” he says. “A lot of these standards have been around for many years and they have been used effectively, but in many ways people weren’t aware of them. You can think of OSAC as the last stop in the process of saying ‘This is it. It’s the Mt. Rushmore of forensic standards.’ So the fact that an ASTM standard, E2329, was the very first one put on the OSAC registry is something all ASTM members should be proud of.”

A place on this registry is more than just a point of pride, however. It also gives the standards listed there additional gravitas among forensic scientists. Susan Hetzel emphasizes that “ASTM standards are voluntary standards. You can choose to follow them or not follow them. Some people use the ASTM standards as a guide and develop their own methods based on what the ASTM standards say. But by instituting the registry process, it’s a way to try and make them follow the standard and not do it their own way because their own way may not be validated.”

Another ASTM standard poised for addition to the OSAC registry is the practice for reporting opinions of scientific or technical experts (E620). First approved in 1977, members of E30 began working to update it six years ago, and it is now in the final stages of review, with approval likely in Spring 2018.

The Quest for Justice

The ultimate goal of any trial or civil proceeding is to achieve a just outcome. While each of the more than 600 members of Committee E30 focus in tightly on the minutiae of their particular discipline, the impact of their work extends far beyond the crime scene and the laboratory.

Vorder Bruegge puts it this way. “Forensic science affects the victims of crime, it affects those who are accused of committing crimes, whether they are guilty or innocent, and it’s critical that science be used not only to convict the guilty but also to exonerate the innocent. So you want to make sure that that is a reliable process and that it meets standards in the community. E30 serves to set that standard across a large part of the community.”

Jack Maxwell is a freelance writer based in Westmont, New Jersey.