Inaccuracies in Forensic Testing

*I am pleased to post an article written by Allison Gamble for Life and Death Matters. She is a contributing writer for forensicpsychology.net and has published extensively on forensics in death penalty and other cases.  Allison has been a curious student of psychology since high school.  She brings her understanding of the mind to work in the weird world of internet marketing.

Within the criminal justice system, a few fundamental problems cause most wrongful convictions in courtrooms all across the country. Unarguably, the most common among these issues are inaccuracies in forensic testing. Trial transcripts cannot tell us whether prosecutors sought to use invalid forensic evidence, but they do show forensic testimony and physical forensic evidence are heavily relied upon during evidence presentations. In a number of trials studied, defense attorneys rarely made any objections when invalid forensic evidence was presented. There is need for reform in the use of forensic evidence that should include enforceable national standards to govern the collection and interpretation of forensic data.

Among 156 exonerated men in the aforementioned study, 60 percent had invalid scientific testimony at their trials. The invalid testimony primarily involved serological analysis and microscopic hair comparison, but also involved bite mark, shoe print, and fingerprint comparisons. The study did not just involve a few forensic analysts in a small number of states. These wrongful convictions were from 72 forensic analysts employed by 52 forensic labs or medical practices in 25 states. All of these trials involved serious charges such as rape and murder, and ten of the trials resulted in death sentences.

One of the forensic examiners in the study made conclusions based on probability when comparing hair samples found at a crime scene. The examiner had no empirical data on which to base these guesses, yet was able to state the hair from the defendant was similar to one from the crime scene. When the examiner was questioned, she admitted she had no statistics by which to compare the sample. It was just her personal opinion.

In the case of Arizona v. Ray Krone, a death penalty conviction resulted from faulty bite mark evidence. Forensic examiners compared bite marks by manipulating photographs to match the bite mark of the victim to impressions from Krone's teeth. Upon appeal, the bite mark evidence was found to be faulty. He was exonerated from the crime after DNA testing identified DNA markers found on the victim's body that did not match Krone's DNA.

At least three convictions have been overturned because of faulty ballistec evidence. In the case of Maryland v. Kulbici, firearms evidence conflicted with every assertion the prosecutors made at trial. There was no evidence of the defendant's gun being recently fired, yet the prosecutor claimed the defendant had just cleaned the gun to hide his crime. Additionally, there was a 30 percent disparity between the striations on the bullet that killed the victim and the striations from the defendant's firearm. The forensic testimony called the two a match, without showing proper data to support that claim. The evidence led to a murder conviction, which was later overturned.

In a case involving fingerprint evidence, the FBI arrested Brandon Mayfield for the Madrid train bombing of 2004. He was identified as the source of a fingerprint taken from a bag of detonators found close to the crime scene. After assigning three of its expert fingerprint examiners to the case, the FBI declared a 100-percent match to Mayfield. The Spanish National Police disagreed with the finding, and declared a match to a man named Ouhnane Daoud. As it turned out, the Spanish authorities were correct, and the FBI withdrew its findings and released Mayfield.

Blood and saliva samples are often used to compare DNA markers to identify assailants. It's commonly thought that DNA technology has solved the problem of invalid forensic testimony. Although it has replaced some traditional forensic methods used to solve criminal cases, most cases are solved without DNA evidence. Further, DNA testing is not immune to inaccurate results. However, since courts routinely deny funding to defense experts, these analysts are not usually cross examined, and the validity of DNA evidence often goes unquestioned.

Often the fault lies with the testimony of experts hired to present forensic evidence. Evidence can be manipulated by the expert testimony of people who are simply embellishing on what the evidence suggests, and these experts aren't being challenged for presenting ambiguous results. There are no regulations to keep these experts in check, and wrongful convictions continue to occur.

If forensic evidence is unreliable, then it has no place in a courtroom. Indigent clients will never be able to challenge inaccuracies in forensic testimony because they simply cannot afford to pay their own experts. This makes the system unequal, and goes against the very fabric of American judicial ideals.

-Allison Gamble


alliegamble812@gmail.com