Forensic Science Reform at ‘Crossroads’

The government’s 2017 decision to shut down the National Commission on Forensic Science has slowed the movement to reform how courts treat forensic evidence, according to a UCLA Law study.

Recent efforts to reform the use of forensic science in the courtroom don’t go far enough to meet widespread criticisms of its validity and reliability, according to a University of California-Los Angeles (UCLA) Law School study.

forensic science

UCLA Law Professor Jennifer L. Mnookin examined the state of forensic science reform. Photo courtesy UCLA

In the last two decades, often-used forms of pattern evidence, such as fingerprint, tool mark, and bite mark identification, have faced significant criticism, wrote study author Jennifer L. Mnookin, a law professor at UCLA, in a research paper posted in Daedalus, a journal of the American Academy of Arts and Sciences.

The Department of Justice’s decision in April 2017 not to renew the charter of  the National Commission on Forensic Science reduces the likelihood of real reform, which Mnookin said puts forensic science  at a “crossroads.”

“Our best hope for sustained, substantial changes necessary for improving forensic science evidence within our system of justice requires the creation of another national commission or other institutional body, made up of both research scientists and other institutional stakeholders,” she wrote.

Mnookin uses a mistaken bite mark identification case to further her point.

Alfred Swinton, was released from prison after serving 18 years of a 60-year  sentence for murder, after an expert admitted ruled the bite mark identification evidence used to convict him no longer seemed persuasive or valid.

The bite mark expert “no longer believed with reasonable medical certainty–or with any degree of certainty –that the marks on [the victim] were created by Mr. Swinton’s teeth, because of the recent developments in the scientific understanding of bite-mark analysis,” odontologist Constantine Karazulas told the Hartford Courant, as quoted by Mnookin.

Is Forensic Science ‘Junk Science’?

Karazulas even called his earlier testimony “junk science” and said he “no longer believes that Mr. Swinton’s detention was uniquely capable of producing the bite marks I observed.”

Mnookin suggested the case indicated a potential sea change for the use of bite mark evidence,  and noted there is a growing consensus among judges that the forensic science community should scale back exaggerated and overconfident assertions of knowledge and authority by forensic scientists.

Mnookin concluded that future reform required an institutional structure adversarial advocates, and practitioners themselves, staffed by accomplished research scientists to pave new ways for credible forensic science evidence to be used in courtrooms.

“We are simply not likely to see continued forward motion unless there is some institutional body to prompt reform, a commission or working group with both convening power and a claim to legitimacy, in which academic researchers and forensic science stakeholders can jointly assess the state of forensic science and continue to push for, and argue about, improvements,” she wrote.

If it can happen, she said, the future of forensic science will almost certainly be far brighter, and the substance of what is used in investigations and offered in courtrooms throughout our nation will be more reliable, more trustworthy, and more scientifically valid.

Additional reading: “Science Takes a Hit at the Department of Justice,” by Jeff Butts, TCR Dec 2018.

A full copy of the report can be downloaded here

Megan Hadley is a senior staff writer at The Crime Report. Comments welcome.

from https://thecrimereport.org

The Psychology of Being Shot

     ….If it takes ten or twelve seconds to lose consciousness from blood loss (and consequent oxygen deprivation to the brain), why, then, do people who have been shot so often collapse on the spot? It doesn’t just happen on TV.

     I posed this question to Duncan MacPherson, a respected ballistics expert and consultant to the Los Angeles Police Department. MacPherson insists the effect is purely psychological. Whether or not you collapse depends on your state of mind. Animals don’t know what it means to be shot, and, accordingly, rarely exhibit the instant stop-and-drop….

     Not everyone agrees with the psychological theory. There are those who feel that some sort of neural overload takes place when a bullet hits….An area of the brain called the reticular activating system (RAS) is responsible for the sudden collapse. The RAS can be affected by impulses arising from massive pain sensations in the viscera. Upon receiving these impulses, the RAS sends out a signal that weakens certain leg muscles, with the result the person drops to the ground….

Mary Roach, Stiff, 2003 

     ….If it takes ten or twelve seconds to lose consciousness from blood loss (and consequent oxygen deprivation to the brain), why, then, do people who have been shot so often collapse on the spot? It doesn't just happen on TV.

     I posed this question to Duncan MacPherson, a respected ballistics expert and consultant to the Los Angeles Police Department. MacPherson insists the effect is purely psychological. Whether or not you collapse depends on your state of mind. Animals don't know what it means to be shot, and, accordingly, rarely exhibit the instant stop-and-drop….

     Not everyone agrees with the psychological theory. There are those who feel that some sort of neural overload takes place when a bullet hits….An area of the brain called the reticular activating system (RAS) is responsible for the sudden collapse. The RAS can be affected by impulses arising from massive pain sensations in the viscera. Upon receiving these impulses, the RAS sends out a signal that weakens certain leg muscles, with the result the person drops to the ground….

Mary Roach, Stiff, 2003 

from http://jimfishertruecrime.blogspot.com/

Bias in Forensic Science

The close relationship that forensic practitioners engender with law enforcement agencies renders them susceptible to cognitive bias through the wider problem of information sharing. Confirmation bias occurs when practitioners use selective external in…

The close relationship that forensic practitioners engender with law enforcement agencies renders them susceptible to cognitive bias through the wider problem of information sharing. Confirmation bias occurs when practitioners use selective external information, consciously or unconsciously garnered from their associates, to assist their conclusions. This is a well-studied phenomenon in eyewitness lineups, in which witnessed who are initially tentative with their identifications become positive after learning that the person they identified is the prime suspect according to the police. Confirmation bias has played a role in numerous forensic scandals, and was recently acknowledged as one of the leading cause of the [fingerprint] misidentification of the 2004 Madrid [train] bomber.

C. Michael Bowers, Forensic Testimony, 2013

from http://jimfishertruecrime.blogspot.com/

The Power of DNA

     Scientists first identified DNA in 1944. Much more recently, early in the twenty-first century, scientists successfully mapped the entire human genome, the sequence of genes on each DNA strand. DNA is found in skin cells, hair, bloo…

     Scientists first identified DNA in 1944. Much more recently, early in the twenty-first century, scientists successfully mapped the entire human genome, the sequence of genes on each DNA strand. DNA is found in skin cells, hair, blood, semen, saliva, even teeth and bone, and analysis of it is carried out by using a computer to compare and attempt to match two samples.

     We shed old skin cells and hair constantly, which is why DNA is so often found at the scene of a crime, and DNA samples can be obtained by swabbing inside the cheek or from an unwitting suspect's cigarette butt, coffee cup, or toothbrush.

     Only identical twins and clones have identical DNA. For anyone not a twin, finding a match between one's DNA and a specimen found at a crime site is as close as one can get to proof that the person was involved in the crime. [More accurately, it's concrete proof the DNA donor was there.] It's still circumstantial evidence, but juries tend to find it sufficient to convict a defendant. In the last few years, hundreds of convicted but innocent felons have been pardoned on the strength of DNA analysis.

Robert Mann, Ph.D. and Miryam Ehrlich Williamson, Forensic Detective, 2004 

from http://jimfishertruecrime.blogspot.com/

The Life of a Corpse: Postmortem Changes

     Climate and terrain have a great impact on the speed with which a body decomposes. If a body is deposited in a wooded area in upstate New York in the dead of winter, it’s going to decompose much more slowly than one dumped in Florid…

     Climate and terrain have a great impact on the speed with which a body decomposes. If a body is deposited in a wooded area in upstate New York in the dead of winter, it's going to decompose much more slowly than one dumped in Florida woods in the summer. One reason is that flies and bacteria, the two main factors in turning a corpse into a skeleton, aren't active outdoors in cold weather. Research shows that bodies placed outside in the winter don't bloat as much as those in the summer, and many of them turn what we refer to as "Halloween colors"--orange and black.

     Although not every case holds true, bodies usually go through several predictable stages: fresh, bloated, and dry. At this last stage, the decomposition process has ceased, maggots have finished feeding, and, unless rodents and larger carnivores eat it, the corpse will change very little even over a period of years. If there is any flesh left covering the skeleton, it will harden so that it will someday resemble leather or parchment paper.

     During the early stages of decomposition, internal gases bloat the abdomen, the skin stretches like plastic wrap, and the veins fill with bacteria, turning them green and black so they look like thin highways or the graining on marble--hence the term "marbling."

     Sometimes, in as little time as two weeks, the face, chin, throat, groin, and abdomen become the first areas to skeletonize. The less meaty and, to maggots, less desirable areas, such as the arms and legs, often decompose last. When you lift a body to look under it, those areas of the body in contact with the ground often resemble Swiss cheese or wormwood; this is where maggots have left the body and burrowed into the ground. Contrary to common belief, hair and nails don't keep growing after death; it's the shrinkage of the tissue that gives this illusion. Skin and hair are dead cells; they were dead before the individual died.

Rober Mann, Ph.D. and Miryam Ehrlich Williamson, Forensic Detective, 2006 

from http://jimfishertruecrime.blogspot.com/

Crime Scene Fiber Evidence

     Fiber evidence can be horrendously confusing. There’s probably about seven thousand dyes and pigments that are used in textiles. Any one of those requires about eight to ten unit processes to turn it into a usable chemical for dyeing. There are about twelve different ways to get dyes into textiles. There’s about twenty-nine different dye categories. Any one color that you see in a garment rarely is the result of one dye. And there’s all types of finishes, both chemical and physical, that change the final properties of the dye.

     And that’s just color. That’s not talking about the categories of polymer….

Fiber specialist in Crime Scene by Connie Fletcher, 2006 

     Fiber evidence can be horrendously confusing. There's probably about seven thousand dyes and pigments that are used in textiles. Any one of those requires about eight to ten unit processes to turn it into a usable chemical for dyeing. There are about twelve different ways to get dyes into textiles. There's about twenty-nine different dye categories. Any one color that you see in a garment rarely is the result of one dye. And there's all types of finishes, both chemical and physical, that change the final properties of the dye.

     And that's just color. That's not talking about the categories of polymer….

Fiber specialist in Crime Scene by Connie Fletcher, 2006 

from http://jimfishertruecrime.blogspot.com/

Forensic Science Versus Eyewitness Testimony

     For lawyers in a courtroom, on-the-scene descriptions and eyewitness observations are valuable assets. Lawyers know from experience that the “plausible” testimony of a “credible” witness can make or break a case. They know that juri…

     For lawyers in a courtroom, on-the-scene descriptions and eyewitness observations are valuable assets. Lawyers know from experience that the "plausible" testimony of a "credible" witness can make or break a case. They know that juries are easily swayed by human testimony, and that if what a witness says sounds correct, juries usually believe it is correct.

     Medical examiners, on the other hand, knowing the ambiguity of appearances and the fickleness of the senses, regard eyewitness reports with a good deal less enthusiasm. In their experience, eyewitness descriptions are often the least reliable of all forensic aids, while scientific testing and objective analysis are the two most important crime solving tools.

     One thinks of the famous Japanese film Rashomon. The story revolves around an episode in which--or so it seems--a merchant and his wife are attacked by a bandit. The wife is raped and the merchant killed. Three people are involved in the drama, plus a woodcutter who witnesses the event. We see the episode from the point of view of each protagonist, and each story is entirely different from the others. Due to their own fears, lies, blindness, subjectivity--who knows?--the three people describing the crime might as well be reporting three separate murders.

Frederick Zugibe, M.D. and David L. Carroll, Dissecting Death, 2006

from http://jimfishertruecrime.blogspot.com/

What is Caliber?

Caliber which is used to describe weapons other than shotguns, has to do with the nominal diameter of the barrel (hence of the ammunition) expressed in hundredths of an inch….Thus, a .38 revolver has a barrel .38-inch in diameter. A .30-caliber rifle fires bullets .30-inch in diameter. Magnum used in a description of a firearm refers not to caliber but to the firepower of the propellant used; however, normally a magnum firearm is a slightly different caliber from the closest caliber of a regular firearm–thus, you have .357 magnums which can fire .38 ammunition, but don’t try to fire .357 magnum ammunition in a .38 revolver; it will fit the chamber and cylinder, but the firing mechanism and the barrel aren’t meant to withstand a magnum load.

Anne Wingate, Ph.D., Science of the Crime, 1992 

Caliber which is used to describe weapons other than shotguns, has to do with the nominal diameter of the barrel (hence of the ammunition) expressed in hundredths of an inch….Thus, a .38 revolver has a barrel .38-inch in diameter. A .30-caliber rifle fires bullets .30-inch in diameter. Magnum used in a description of a firearm refers not to caliber but to the firepower of the propellant used; however, normally a magnum firearm is a slightly different caliber from the closest caliber of a regular firearm--thus, you have .357 magnums which can fire .38 ammunition, but don't try to fire .357 magnum ammunition in a .38 revolver; it will fit the chamber and cylinder, but the firing mechanism and the barrel aren't meant to withstand a magnum load.

Anne Wingate, Ph.D., Science of the Crime, 1992 

from http://jimfishertruecrime.blogspot.com/

What is Trace Evidence?

     Trace evidence analysis is the section of the crime lab where, if they don’t know where to send it, they send it to us. We get all kinds of oddball things in here. Feathers. We’ve had feathers come into the crime lab. Bird feathers….

     Trace evidence analysis is the section of the crime lab where, if they don't know where to send it, they send it to us. We get all kinds of oddball things in here. Feathers. We've had feathers come into the crime lab. Bird feathers.

     One case: A person was shot and killed outdoors, near a garage. The bullet went through the victim's down jacket. And then it hit a garage door and deflected off. In that garage door, in the bullet hole, there was a little feather. I think the defense's story was that the shooting was accidental, that the defendant had aimed at the garage, and the bullet deflected off it, and then it went into the victim.  We couldn't say for sure that the bullet hole feather was from the victim's jacket, but finding it on the garage door corresponds more to the person being shot and then the slug entering the door. The victim was hit first.

Trace evidence analyst in Crime Scene by Connie Fletcher, 2006 

from http://jimfishertruecrime.blogspot.com/

Dr. William Maples on Forensic Anthropology

     A forensic anthropologist is not a medical doctor, though he has a Ph.D. and has studied anthropology in college. We specialize in the human skeletal system, its changes through life, its changes across many lifetimes, and its varia…

     A forensic anthropologist is not a medical doctor, though he has a Ph.D. and has studied anthropology in college. We specialize in the human skeletal system, its changes through life, its changes across many lifetimes, and its variations around the world. We are part of the larger field of physical anthropology, or biological anthropology as it is known today, which is concerned overall with the human body and all its variations. My specialty, physical anthropology, is distinct from other fields such as cultural anthropology and archaeology....

     My field of expertise is the human skeleton. Though some pathologists insist on doing their own skeletal examinations along with autopsies, I can confidently say that there are very few cases in which a forensic anthropologist--someone like me--could not add a great deal of useful information to what a pathologist can discover. I have had pathologists exclaim frankly in my hearing, when confronted with a skeleton: "Gee, I'm not used to looking at these without the meat on them!"

Dr. William R. Maples, Dead Men Do Tell Tales, 1994

from http://jimfishertruecrime.blogspot.com/