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Forensic Science: Bodies of Evidence

Let us call the textbook forensic archaeology case related by Kimberlee Sue (Lange) Moran '00 as "The Case of the Bulldog Shovel"…

"A girl had gone missing, and the chief suspect was her father," says Moran, a forensic archaeologist in England. "There was a large time gap that he couldn't account for, and his credit-card record indicated that he had recently bought a new shovel. First, the police needed to find the body. A map of the man's route between work and home showed a wooded lay-by, or pull-off, along the highway, where the forensic archaeologist on the case found several areas of ground with clear signs of disturbance. He excavated one location and found the body of a dog. He excavated another disturbed spot, and although there was nothing in it, there was a broken tree root, which often occurs as someone begins to dig a grave and hits roots or stones that make the going difficult. He tried again a few feet away and, sure enough, found the girl's body. Although there was little helpful evidence in the grave, an examination of the broken tree root showed green paint, which was a perfect match with the distinctive green paint on the father's new Bulldog-brand shovel. It was not the only piece of evidence that was used to convict the father, but it was significant."

Underground Crime Scene

Kimberlee Sue (Lange) Moran
Kimberlee Sue
(Lange) Moran '00

Forensic archaeology, which was pioneered in the United Kingdom, is a relatively new field. Moran, a program director for Forensic Outreach, based in London, advises law enforcement agencies regarding excavation of buried items, body recovery, and fingerprinting enhancement.

The case illustrates the fact that the most valuable crime evidence sometimes has nothing to do with the body. "My responsibility is to recover buried evidence and to apply my skills as an archaeologist to retrieve as much information as possible—not just what was buried, but how and when it was buried and what tool or tools were used," explains Moran.

"It's very similar to being a crime-scene investigator," Moran observes, "except that my crime scene is underground."

Moran assists police in collecting, packaging, and recording the recovered evidence. Just as she would do at a traditional dig, "At every stage of the excavation, we photograph and produce a scale drawing both in profile and plan view of the site and everything that comes out of the ground, and we keep very detailed notes. We also want to preserve the cut of the hole so that we can make a cast of the edge to work out the size and shape of the tool that was used. Sometimes we can also recover a footprint under the object that was buried."

Moran, who majored in classical and Near Eastern archaeology at Bryn Mawr, observes that just as in classical archaeology, "My most important tools are a trowel, a dustpan, and a popsicle stick!"

Forensic science is a multidisciplinary field, which relies on collaboration among archaeologists, biologists, chemists, and environmental scientists to recover and analyze evidence. For example, an environmental scientist may be called in to use ground-penetrating radar to survey a large area for signs of disturbance. In one case, a soil sample recovered from a body by Moran's team was analyzed by a palynologist, or pollen scientist, who identified grains of pollen that were then traced to the suspect's back yard.

Ultimately, Moran says, "I am responsible for giving an interpretation of the site, but it is the other experts in the forensic lab who examine what I recover from the excavation."

DNA Profiling

Susan Welti
Susan Welti '97

As a criminalist in the New York City Office of the Chief Medical Examiner, Susan Welti '97 relies first on her senses, in particular, sight and touch, to identify traces of biological substances on evidence. A supervisor in the Homicide/Sex Crimes group, Welti's team works on evidence recovered from homicides, assaults, and sexual assaults.

"We examine a multitude of different types of evidence," explains Welti, who majored in biology at Bryn Mawr. "For example, we might examine a sexual assault kit, clothing, and/or bedding from a sexual assault, or a weapon, such as a knife, and clothing in a homicide. We are generally looking for blood, saliva, or semen on the evidence, but we may also look for skin cells from the handle of a knife to see who might have held it. If we find any of these biological substances, we then try to obtain a DNA profile from them."

DNA profiling has been used since the early 1990s. First, polymerase chain reaction is used to amplify, or copy, nuclear DNA through in vitro enzymatic replication. In the process, fluorescent dyes are attached to 13 different sections of non-coding DNA. The samples are then separated by size using electrophoresis, and a laser is used to detect the fluorescent dyes. In this way, short tandem repeats of nucleotides in these regions can be visualized and analyzed, enabling the scientist to identify the individual's DNA profile.

Although it may seem counterintuitive that the DNA profile focuses on non-coding DNA, which does not code for a protein that would determine a physical characteristic such as the color of skin, eyes, or hair, this approach provides an objective, unbiased means of identification.

Still, there are limitations. "There may not be enough biological material on the evidence to obtain a DNA profile, or there may be biological material from more than one person creating a mixture of DNA," Welti explains. "We also cannot determine at what point in time that biological material was left on the object—it could have been prior to, during, or after the crime—and it is up to the judge or jury to draw such conclusions."

In recent years, DNA profiling also has been used to shed new light on old crimes; in some cases, it has been used to overturn convictions from decades past. "The biggest limitation is how well the evidence was stored," Welti says. "Heat and moisture can break down DNA into smaller pieces, which can make testing difficult if not impossible."

One option that scientists can use for cases involving degraded DNA is mitochondrial DNA rather than nuclear DNA testing. "This requires very specialized testing and provides less information, but it can be used on very old or degraded samples," Welti says. For example, the U.S. Armed Forces DNA Identification Laboratory, where she previously worked, uses mitochondrial DNA profiling to identify soldiers' remains dating from World War II.

Mental State

What if a defendant were to plead legal insanity, or questions were raised about his or her capacity to participate in the defense at trial? Enter the forensic psychologist or psychiatrist.

Carol Holden
Carol Holden '81

Carol Holden '81, director of evaluation services at Michigan's Center for Forensic Psychiatry in Ann Arbor, evaluates criminal defendants who raise issues about their competency to stand trial, or their mental health at the time of the alleged offense. The center is tasked with performing all court-ordered evaluations of criminal defendants for the criminal courts throughout Michigan, and is also a 210-bed maximum-security treatment facility for individuals who have been found incompetent to stand trial or acquitted by reason of insanity.

Contrary to popular notion, in the United States the insanity defense is rarely raised and even more rarely is it successful: fewer than two in 10,000 criminal defendants successfully plead legal insanity. "Most of the statutes are fairly conservative; few defendants meet the criteria for mental illness or mental retardation, and even fewer meet additional criteria set by individual states," Holden explains. "Another reason is that offenders spend far longer in the mental-health system than they would have spent in prison had they just pleaded guilty.

"Finally, juries hate it: they think that it's an easy defense, and they think that people 'walk' even though neither of those beliefs is true," Holden says. "So it is not unusual for someone to have a very strong argument for insanity and for the jury to say, in effect, 'We simply don't care.'"

A court-ordered psychological evaluation includes an examination of the police report, as well as other pertinent documents, such as clinical records and educational records. The evaluator may interview law enforcement personnel, forensic scientists, and witnesses, and, in some cases, administer standardized psychological or cognitive tests to the defendant.

But at the heart of the evaluation are one or more interviews with the defendant. "When I am trying to determine legal insanity, the core of the interview focuses on as detailed an account as I can get of what happened, in the defendant's view, on that day," Holden says. "I collect a social history as I would from anybody, but it tends to be brief; I am far less interested in early childhood experiences than I would be in a clinical context. I am most concerned with mental illness, cognitive impairment, substance use, and previous psychiatric and medical histories."

Competency to stand trial is a here-and-now question about whether defendants understand the nature and object of the proceedings against them, and whether they can assist their attorney in a rational manner. "Along with a general clinical interview, I am asking questions focused on their understanding of the charges against them, their plea options, and their procedural rights," Holden says.

The courts are clear about the criteria for legal insanity, says forensic psychiatrist Sarah Leisenring '89, program manager and supervising psychiatrist in the Program for Forensic Evaluations in Corrections and the Community at Western State Hospital in Tacoma, Wash. "The courts require a diagnosis of a major mental illness—schizophrenia, major depression, bipolar disorder, or generalized anxiety disorder," she explains.

Leisenring, who majored in chemistry, says forensic psychiatry has no equivalent to a DNA profile. "There are no definitive objective tests that can show that someone was suffering from schizophrenia at the time that they committed a crime; we have to put together a clinical picture from their history and present symptoms," she says. "The evaluation is also limited by the experience and abilities of the examiner. We are responsible for keeping up on our clinical skills and making sure that any personal feelings we might have about a particular crime do not influence our ability to make an objective opinion."

Holden agrees. "The limitations are obvious: there is no way to know what is actually going on in someone else's head," she observes, "and like any field that relies on expert opinion, there are good and bad practices, and good and bad experts.

"The strength of forensic psychology is that there is considerable consensus about what reasonable practice should be and there is a growing professional literature," Holden says.

Sex Offenders

Barry Zakireh
Barry Zakireh, Ph.D. '99

Psychological evaluation of sex offenders poses special challenges, says Barry Zakireh, Ph.D. '99, director of the Adult and Forensic Program at the Joseph J. Peters Institute, Philadelphia. "Most offenders, even after conviction for a sex crime, try to deny or minimize wrongdoing because there is a lot of stigma," he explains. "The sense of shame associated with committing a sex crime far outweighs other crimes. I have had people admit to killing someone long before they would admit to committing a sex crime. Even among prisoners, sex offenders are considered the lowest type of criminal."

Cultural norms also affect the defendant's willingness to discuss certain issues. "There are vast cultural differences, and they are laden with value judgments," Zakireh says. "Among Latinos, for example, certain behaviors are very much taboo. Homosexual behavior is difficult for people to acknowledge. Other behaviors, such as incest, are expected to be handled within the family, and intervention by outside agencies creates resistance to disclosure."

Zakireh evaluates defendants in criminal and civil cases. These include pre-trial and investigation phases of criminal trials as well as post-incarceration and parole cases. For civil proceedings, he is involved in voluntary, agency-ordered, and court-ordered evaluations related to sexual misconduct, criminal sexual behavior (sexual offenses), child custody, and sexual behavior issues. As a member of the Commonwealth of Pennsylvania Sexual Offender Assessment Board, he evaluates adults to whom Megan's Law provisions may be applicable, and young offenders who are subject to Pennsylvania's Act 21, which requires civil commitment for sexually dangerous older juveniles and young adults who have been in custody at a juvenile facility until age 21.

Zakireh says there are special challenges involved in the evaluation of juvenile sex offenders, in particular. "One of the big mistakes is to lump all sex offenders together in one category," he says. "That is true for adults, but is particularly true for juveniles. There has been a movement in this country to treat juveniles as adults, including placing them on registries of sex offenders, even if as a 12-year-old their only crime was touching another child at school.

"Few practitioners in this field are knowledgeable of the developmental issues of childhood and adolescence, including sexual behavior," he says. "In addition, the interviewing techniques that one applies to juveniles are quite specialized."

Challenges and Rewards

Dealing with the daily reminders of the human capacity for violence is one of the challenges for forensic scientists. "Like anyone in the criminal justice system, we are seeing people at the worst times in their lives, and often the events leading to their arrest are awful," Leisenring observes. "We have to avoid the tendency to think badly about other human beings when we are working solely with this population."

They also confront issues of inequality. "For me, the sense that some people never had a chance—for social, economic, or family reasons—can be overwhelming," Holden says.

However, these forensic scientists say that their work is intellectually challenging and rewarding. "I believe that as flawed as our criminal justice system is, it is a really good one, and that I can help in a meaningful way to see that justice is done," Holden says.

"It is rewarding for me when I see someone for evaluation or treatment and observe the changes that person is able to make cognitively and emotionally over time," Zakireh says. "The majority of sex offenders do want to change their lives."

For Welti, the inscription on the building in which she works says it best: "'Science serving justice.' That summarizes what we do, and it is very satisfying."

About Our Sources

Carol E. Holden '81 is director of the Evaluation Services at Michigan's Center for Forensic Psychiatry, Ann Arbor, which provides diagnostic services for the state's criminal justice system. An adjunct assistant professor of psychology at the University of Michigan, Ann Arbor, Holden has taught clinical assessment to graduate students and introductory psychology courses to undergraduates. In her private practice, Holden evaluates juvenile offenders for the courts. She earned her doctoral degree in clinical psychology at the University of Michigan, Ann Arbor. She is certified in forensic psychology by the American Board of Professional Psychology.

Sarah E. Leisenring '89 is a program manager and supervising psychiatrist in the Program for Forensic Evaluations in Corrections and the Community at Western State Hospital, Tacoma, Wash. Leisenring earned a medical degree from the University of Colorado Health Sciences Center. She earned a master's degree in biophysical chemistry from Yale University on a Blodgett Scholarship from the General Electric Foundation. She is certified by the National Board of Medical Examiners and the American Board of Psychiatry and Neurology; she also holds a certification in the subspecialty of forensic psychiatry.

Kimberlee Sue (Lange) Moran '00 is a program director for Forensic Outreach, an independent organization that provides forensic training, consulting services to law enforcement agencies, and educational programs in secondary schools. She earned a master's degree in forensic archaeology from the Institute of Archaeology, University College London. She is currently a doctoral candidate in archaeology at the institute, specializing in ancient fingerprints. Her research involves examination of administrative use of clay seals through fingerprint evidence, and artificial cranial deformation and its occurrence in the Near East. She is developing a fingerprint database for the ancient world.

Susan E. Welti '97 is a criminalist in the New York City Office of the Chief Medical Examiner, where she conducts scientific analyses, including DNA profiling, on physical evidence. Prior to this, she was a DNA analyst with the Armed Forces DNA Identification Laboratory, where she performed DNA-typing services for federal and military law enforcement agencies. Welti earned a master's degree in forensic sciences at George Washington University.

Barry Zakireh, Ph.D. '99, is director of the Adult and Forensic Program of the Joseph J. Peters Institute, Philadelphia, which provides forensic evaluation and treatment of adult sexual offenders. Referring agencies include the Philadelphia County Adult Probation Department, the Pennsylvania Board of Probation and Parole, and the Bureau of Community Corrections. His private practice focuses on clinical and forensic psychology with adults and juveniles. Zakireh earned a doctoral degree in clinical developmental psychology from Bryn Mawr. He earned a master's degree in psychology from the New School for Social Research, and a bachelor's degree in sociology from Temple University.


Dorothy Wright contributes news and feature articles on science, technology, engineering and general-interest topics to a variety of publications, including Civil Engineering and Engineering News Record.