CHAPTER 4 FORENSIC SCIENCE EVIDENCE
| Jurisdiction | United States |
After reading this chapter, you should be able to:
• Distinguish intentional misconduct from other types of forensic science issues that contribute to wrongful convictions.
• Understand the role that cognitive bias plays in the analysis of forensic science evidence.
• Discuss the rules of evidence and case law governing the admissibility and reliability of expert testimony, including Daubert and Frye.
• Understand the Sixth Amendment right of criminal defendants to confront and cross-examine forensic analysts.
• Discuss the National Research Council's 2009 critical report on forensic science in the U.S.
• Appreciate the value of forensic science oversight commissions.
Santae Tribble was 17 years old when he was convicted of the murder of Washington, D.C., taxi cab driver John McCormick in 1978. McCormick was shot and killed on his front porch during the course of a robbery after he had finished his shift and was returning home. The only witness to have seen the masked assailant was McCormick's wife, who had viewed the robber from a window of the home. Soon after the incident, a police officer found a stocking mask assumed to have been worn by the robber on a sidewalk near the McCormick's home. Tribble and his friend, Cleveland Wright, were implicated in the robbery and shooting of John McCormick through an informant who told the police that Cleveland had sold her roommate a handgun that fit the description of the one used to kill McCormick. The informant also told the police that Santae had made admissions of guilt to her related to the killings. Tribble and Wright were charged with the robbery-murder of McCormick as well as the separate robbery and murder of William Horn, whose prior killing had occurred under similar circumstances to McCormick's killing (United States v. Tribble, 2012).
The stocking mask found near the scene of McCormick's murder was sent to the FBI Crime Laboratory for analysis. The agent who conducted the analysis testified at Tribble's trial for McCormick's murder that one of the hairs found in the mask matched Tribble's hair "in every microscopic characteristic" (United States v. Tribble, 2012, p. 1). In addition, the prosecutor stated in closing arguments to the jury that there was "one chance ... in ten million" that the hair belonged to someone other than Tribble (United States v. Tribble, 2012, p. 1). Tribble was convicted in 1980 and sentenced to 20 years to life in prison. He was paroled in 2009.
In 2012, investigative journalist Spencer Hsu of the Washington Postbegan reporting on a federal task force that was convened in the 1990s to review deficiencies involving unreliable forensic evidence at the FBI Laboratory (Hsu, 2012). The task force review had focused on 13 laboratory examiners, one of whom, Michael Malone, worked in the hair and fibers unit. The crux of the Washington Post investigation was that scores of defendants were not made aware of findings that deficient analysis and testimony may have led to the convictions of innocent defendants. In addition, argued Hsu, the task force should have extended its focus in the Hair and Fibers unit to examiners beyond Malone, as the problems were widespread (Hsu, 2012).
What does all this have to do with our story of Santae Tribble? Tribble is one of three District of Columbia men (Donald Gates and Kirk Odom were the others) who were convicted based on overstated hair comparison testimony provided by FBI examiners and later exonerated. These cases illustrate just one of the multiple ways in which forensic science evidence can contribute to wrongful convictions.
The Washington Tost—Since 2012, Spencer Hsu has been writing for the Washington Post about flawed FBI hair testimony and other forensic science issues. His article, "Convicted Defendants Left Uninformed of Forensic Flaws Found by Justice Dept.," discusses the Tribble case and others.
History of U.S. Torensic Errors (2012)—In this C-SPAN video, Hsu discusses his Washington Post articles on forensic errors and takes calls from the public.
Tribble's case is one of many exonerations involving forensic science errors at the trial stage. According to the National Registry of Exonerations, false or misleading forensic evidence was a contributing factor in 24% of the first 2,030 exonerations since 1989. Among DNA exonerations, the proportion is about half. During the two decades that Santae Tribble was incarcerated, considerable changes were underway in the world of forensic science evidence. In 1980, when Tribble was convicted, the forensic use of DNA had yet to be established. Three years before Tribble was officially declared innocent in 2012, the National Research Council of the National Academies of Sciences published a report ("NRC Report") that scrutinized forensic science (National Research Council, 2009). In many ways, the NRC Report was not encouraging— it found that many of the forensic sciences, like the microscopic hair comparison used to convict Tribble, did not rest on solid scientific foundations.
Research has shown that problems with forensic science evidence can arise in many ways. There can be mistakes or intentional misconduct with regard to testing evidence in the crime laboratory. Likewise, mistakes or intentional misconduct may occur during expert witness testimony at trial. Researchers attribute these problems to a variety of factors including pro-prosecution bias, cognitive biases, poor training, lack of oversight, and more. Furthermore, as noted above, many forensic science disciplines that have been relied on for years to secure criminal convictions lack scientific validity.
Mistakes and Intentional Misconduct in the Lab and at Trial
No national database systematically compiles instances of intentional misconduct among forensic analysts who conduct laboratory analyses or provide trial testimony. Giannelli (1997; 2007) documented several cases of forensic analyst misconduct across the country. One of the more well-known cases concerned Trooper Fred Zain, who was a serologist with the West Virginia State Police. Serology involves the identification and characterization of biological stains for forensic purposes, including ABO blood types. Over the course of a decade in West Virginia, Zain systematically engaged in misconduct in the laboratory and at trial. His misdeeds came to light when Glen Dale Woodall, wrongfully convicted of kidnapping and sexual assault, was exonerated. Zain provided the crucial testimony against Woodall at trial, stating that Woodall's blood type could only be shared with "six in ten thousand" members of the population and that a single red hair found in the victim's car was "highly unlikely" to have come from anyone else (Scheck, Neufeld, & Dwyer, 2003, p. 143). Following Woodall's settlement with the state for $1,000,000, the Supreme Court of Appeals of West Virginia appointed a judge as a special investigator to investigate the allegations of Zain's misconduct. The judge's report found that Zain's misconduct included:
(1) overstating the strength of results; (2) overstating the frequency of genetic matches on individual pieces of evidence; (3) misreporting the frequency of genetic matches on multiple pieces of evidence; (4) reporting that multiple items had been tested, when only a single item had been tested; (5) reporting inconclusive results as conclusive; (6) repeatedly altering laboratory records; (7) grouping results to create the erroneous impression that genetic markers had been obtained from all samples tested; (8) failing to report conflicting results; (9) failing to conduct or to report conducting additional testing to resolve conflicting results; (10) implying a match with a suspect when testing supported only a match with the victim; and (11) reporting scientifically impossible or improbable results. (In the Matter of an Investigation of the West Virginia State Police Crime Laboratory, Serology Division, 1993).
By the time the judge's report was released, Zain had moved on to Texas, where his egregious misconduct continued to contribute to wrongful convictions of others, including Gilbert Alejandro (Scheck, Neufeld, & Dwyer, 2003). At Alejandro's trial for aggravated sexual assault, Zain falsely testified about the DNA tests he had conducted on semen found on the victim. He stated that the DNA "only could have originated from [Alejandro]" (Scheck, Neufeld, & Dwyer, 2003, p. 151). Zain also testified that, "There was no information whatsoever, beyond a scientific reasonable degree, that the particular semen stains that would show they originated other than from him" (Trial Transcript, 1995). Subsequent evaluation of Zain's work and testing of the evidence by another analyst showed that Zain's work had been deficient and that the DNA tests actually excluded Alejandro as the source of the semen.
More recently, Annie Dookhan, formerly a forensic chemist with the now-closed Massachusetts Department of Health Forensic Drug Laboratory, also engaged in systematic evidence tampering and report falsification. Like Zain, Dookhan engaged in "drylabbing" or fabricating results for laboratory tests that were not conducted. She also tampered with negative drug samples to make them positive. Dookhan tested drugs in the laboratory from 2003 to 2012. In 2013, she pleaded guilty to 27 counts related to her misconduct and was sentenced to three to five years in prison. She was paroled in 2016 after having been incarcerated for three years. The reach of Dookhan's misconduct extended to over 24,000 cases (Rosen, 2017). At the beginning of 2017, the state's highest court ordered prosecutors across the state to implement a protocol for dismissing cases involving "Dookhan defendants" (Bridgeman v. District Attorney for the Suffolk District, 2017).
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