

How accurate is DNA testing ? Image Credit: CC BY-SA 3.0 Christoph Bock

Legal authorities in Texas have identified worrying errors in the way labs have been analyzing DNA.

DNA testing has long been regarded as a highly reliable forensic tool that has proven invaluable in countless criminal investigation cases - but just how easy is it for a mistake to be made ?Officials at the Texas Forensic Science Commission recently discovered that labs had been producing inaccurate results by using outdated protocols when analyzing DNA samples.In one case for example DNA recovered from a crime scene was deemed to have a million to one certainty of matching the suspect. When the same DNA test was conducted again with the new protocols however this changed to a probability of thirty to one - a very different result."We have to go back and identify which of those cases involved DNA mixtures where the lab may have given incorrect results," said Galveston district attorney Jack Roady. "It's going to be a herculean task, but we're gonna do it.""The fact that this science may not have been done correctly in the past gives us great pause."The issue appears to relate mainly to laboratories that have been using state-of-the-art testing kits to extract tiny traces of DNA from crime scenes. While this in itself is not a problem - many of these labs have been analyzing their findings using outdated methods that are not really suitable for obtaining accurate results from such 'weak' samples.It isn't clear how many, if any, case outcomes may have been skewed by this issue but if even the chance of an erroneous conviction exists due to incorrect DNA results it does raise questions over whether the faith people maintain in DNA testing as a forensic tool is well founded.