I did not realize the distinction between “low-template DNA” and the full DNA profiles that are generally considered to be extremely reliable. The so-called LTDNA profiles can be generated from a few cells, but often do not have enough material to build a reliable profile. While the reliability of DNA testing is well-known, and generates a high level of confidence, the distinction between those reliable profiles and the LTDNA profiles has not been publicly covered as much. People hear DNA evidence, and they jump to conclusions where there are wildly differing types of DNA evidence.
David Balding, a researcher in London, has developed new software to evaluate the reliability of LTDNA. Geneticist Peter Gill says that implementation of this type of evaluation is long overdue. He says that methods to evaluate and interpret LTDNA currently in use are ineffective. Such evidence may be excludable in U.S. courts if it does not meet the reliability standard to be admitted into evidence.The difficulty in providing a full profile, coupled with the possibility of contamination affect the probabilities of accuracy in determining identification. DNA contamination, due to a poorly handled crime scene, was one of the issues that caused the murder convictions against Amanda Knox and Rafaelle Sollecito to be overturned. Balding’s software indicates that it was very unlikely that Amanda Knox was at the scene of the crime in this case.
As the case is headed for retrial, there is time for there to review the reliability of the DNA and/or LTDNA evidence and its implications on Knox’s guilt or innocence. Hopefully, only evidence that is scientifically reliable will be considered in the final determination on the case.