Mr. Stephen D. Aarons (Santa Fe, New Mexico) was the assigned public defender for a Navajo man named Mr. Theodore Largo. Up until the week of the trial, July 26-29, 2010, Theodore had been sitting in jail for 16 months. In Federal Court, the FBI crime lab's enormous interpretive flaws were fully dissected in front of the jury. Mr. Largo was found not guilty on all counts and immediately released.
The prosecution's scientific case was simple: 4 anal swabs had been collected from a young alleged victim. The FBI lab report stated "….semen identified". Mr. Aarons contacted SFR to examine the FBI lab report. Dr. Spence immediately asked Mr. Aarons to request discovery - all of the supporting scientific documentation. The FBI lab documents pointed to a "Faint Positive" screening test on two of the four swabs. Defying logic, NO effort was made to identify sperm cells on the evidence swabs via microscopic searches. Instead, they proceeded to test ONE of the four swabs for DNA. This strategy revealed NOTHING suggesting the possible presence of Mr. Largo's DNA. Despite this glaring chasm in their scientific case, FBI Lab management refused to back off from their conclusion of "….semen identified".
Dr. Spence informed Mr. Aarons that the FBI lab's conclusions were entirely unjustified, inappropriate, and an enormous misrepresentation of the scientific facts. Dr. Spence backed up that opinion by having the swabs tested (Independent Forensics, Hillside, Illinois) with a more accurate, SPECIFIC screening test for semen, as well as a more sensitive, more thorough DNA testing strategy. The independent outsource lab revealed NO indication of semen and SUPPORTED the FBI Lab's finding of NO DNA linking Mr. Largo to any criminal act.
The screening test utilized by the FBI lab was an ultra-sensitive detection system for a protein that is abundant in semen, ....prostate specific antigen (PSA). The error of leaning too heavily on a PSA test is that recent years have revealed the presence of PSA in body tissues and fluids OTHER than semen. For the defense, the PSA and ZERO DNA issues were illuminated by Richard Coughlin, Ph.D. (President/Chief Scientific Officer of Sequela, Falmouth, Maine), Karl Reich, Ph.D. (Chief Scientific Officer, Independent Forensics), and Michael Spence (Spence Forensic Resources). Refer to the link for elementary information addressing the forensic detection of PSA.
The prosecution's entire scientific case hinged upon a $1.05 PSA detection cartridge produced by Seratec, a German biotech company. Hidden in the FBI's documentation was the "FT POS" notation, indicating the apparent presence of ONE protein. NO attempt was made to find any sperm cells, and two laboratories revealed a conspicuous ABSENCE of any incriminating DNA. It was no surprise that the jury took only a few hours to grant Mr. Largo his immediate release.
There is nothing fundamentally wrong with the PSA tests, ....when they are employed strictly as screening tools, ….pointing the way to the Holy Grail of Forensic Biology, …….DNA. PSA is anything but THE de facto means to establishing a crime. Management associated with ANY forensic biology lab (law enforcement or private enterprises) should interpret certain data with extreme caution.
http://www.spenceforensics.com/fascinatingcases.html
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