Yesterday, CBS News reported an Indiana woman Lana Canen was freed over bad fingerprint evidence after 8 years in prison for a murder she did not commit. Sadly this is not the first time such a mistake has occurred. All too often courts, police, prosecutors, and defence lawyers place too much reliance on seemingly infallible forensic evidence. In 2007 I wrote a paper on the topic of fingerprint evidence entitled: “The Assumptions of Fingerprint Evidence in Canada and the Need for Reform”.
Overall, the use of fingerprint evidence is a reliable form of forensic evidence but one cannot lose sight of the fact that from time to time mistakes are made, and that the entire “science” is premises upon an assumption that every person has a different and distinguishable fingerprint that anyone else. As common as this latter assumption may be held, it has never been proven to be so, just as it has never been “proven” in the formal use of the word that no two people share the same DNA. This is why when asking a true scientist (and not a police officer trained in forensic courses) about the “matching” of DNA, they will answer on a scale of probabilities, and not with complete certainty. For example, the chances that two people would coincidentally share the same DNA profile (depending on the technique being used to conduct the test) may be in the trillions. Although for all intents and purposes this is a “match” it is significant to note the distinction in language used. The language derived from a true scientific method in DNA concedes that it has never been “proven” that no two people share the same DNA (unless they are identical twins unaffected by environmental factors and/or mutations that may have affected their DNA).
Conversely, the science of fingerprints just takes this for granted. It may be a very valid point to say that in X amount of years, we have never come across two that match, that isn’t very helpful when one is only looking to match and not to exclude. However, query the possibility if fingerprints matching had developed a need to try and show that people can have the same fingerprints, or fingerprints that are indistinguishable from detention methods. I would hazard a guess that searching for error over searching for matches would generate a very different view on fingerprint evidence – incidentally, this is the proper scientific method in that assumptions are sought to be disproven, rather than simply confirming the theory. Please read my paper noted above for more on this.
Here is a chart of some of the more famous cases, that we can now add Lana Canen to:
|Case||Error / Detection||Commentary / Results|
|1997 (Strathclyde, U.K.) – Detective Constable Shirley McKie is wrongly accused of being at the scene of a murder and charged with perjury for denying he presence after her alleged fingerprints are found.Analysts at the Scottish Criminal Records Office strenuously denied the print could have been left by anyone else.||Cst. McKie was convicted of perjury. She fought the expert testimony and later won an appeal.A report by Her Majesty’s Chief Inspector of Constabulary also confirmed the error. The fingerprint experts who testified against the Ms. McKie were suspended.||One of Britain’s leading experts in the field, raises a number of concerns about the reliability of the crime detection system and urges it is in need of reform.Shirley McKie: “And they were prepared to do that to me, so I mean, who else? Who else is in jail just now because of fingerprint evidence?”|
|1997 (Massachusetts, USA) – Stephan Cowans||Mr. Cowens was convicted f shooting a police officer. Police linked to a fingerprint on a mug of the shooter. He was sentenced to 35 years in prison until DNA evidence exonerated him years later.|
|2004 (Oregon, U.S.) The FBI arrests Brandon Mayfield for his alleged involvement in the Madrid Train Bombing. Mayfield was never charged but detained for over two weeks before being released upon FBI acknowledging their error.||After Mayfield’s arrest, Spanish authorities raise doubts to the FBI that the fingerprint found at the scene matches Mr. Mayfield’s. Spanish authorities later announce the fingerprints belonged to an Algerian national, Ouhnane Daoud and not Mr. Mayfield. Mr. Mayfield is released shortly thereafter.||The FBI internal review later acknowledged serious errors in their investigation.On November 29, 2006, the U.S. government settled part of the lawsuit with Mayfield for a reported 2 million dollars. The United States government issued a formal apology to Mayfield as part of the settlement.  Brandon Mayfield: “Even though I was arrested as a material witness, don’t be confused,” Mayfield told NEWSWEEK in a phone interview Friday. “They were telling the judge and the world that they’ve got a fingerprint that’s a 100 percent match … What are the implications of that, legally? It’s a death sentence.”|