The issue of forensic hair testimony in Willie’s remaining case was clarified last month by D.H. Kaye in three posts on his blog, Forensic Science, Statistics & the Law (see here, here and here). Kaye discussed the errors made by the FBI hair expert at Willie’s trial, as detailed in two letters which the Department of Justice sent in quick succession shortly before Willie’s scheduled execution in May 2013.
The first letter revealed the error made when the FBI hair analyst gave the jurors a general explanation of microscopic hair comparison: he wrongly ‘stated or implied’ that a hair could be ‘associated with a specific individual to the exclusion of all others’.
The second letter focused on an error that was arguably more significant: in a written report the analyst stated unequivocally that some of the hair fragments were ‘of Negroid origin’, and in testimony he described them as being ‘African American’. We are told that this ‘exceeded the limits of science’: he should instead have testified that the hair exhibited traits associated with African Americans. Kaye’s analysis last month highlighted the invalidity of such testimony according to the Department of Justice’s standard.
The prosecutor drew on both the errors. The first error allowed him to narrow the options, relying on the “statistical weight” that had been wrongly attributed to microscopic hair comparison. The second error was amplified. The prosecutor not only described the hair fragments as African American in origin, he also linked it to aspects of the case which the jurors had been led to associate with Willie:
“How many people could leave those hair fragments, left the house with the gun and the gloves, was trying to sell a ring and a watch like Jon Steckler’s, and also had the jacket from John Wise’s car…?”
As stated in Willie’s Reply to State’s Opposition,
“The FBI agent provided false testimony that was then used by the prosecutor at trial to suggest to the jury that Mr Manning was in the victim’s car.”
Two days after the second letter about hair testimony was sent, a third letter followed, discrediting the FBI ballistics expert testimony given at Willie’s trial. Robert Dunham, executive director of the Death Penalty Information Center, neatly summarizes the implications:
“two different types of junk science masquerad[ed] as forensic evidence of his guilt.”
The Mississippi Supreme Court gave no reason for finally staying Willie’s execution and later granting him DNA and fingerprint testing. But according to ThinkProgress,
“Manning’s defense attorneys are confident that FBI failures were responsible.”
It is a bitter irony that the systematic error of FBI experts, so crushing to Willie at his trial, may, in its exposure 20 years later, allow him finally to prove his innocence.