“An inmate who spent two decades on death row before DNA evidence exonerated him walked out of prison a free man Friday, saying he just wanted to get home and be with his family (Billiot, 2003).” We read about these cases in the newspaper and rightly congratulate ourselves for developing technology that will make our world safer. Genetic Fingerprinting, or matching DNA tests to conclusively tie a suspect to the scene of a crime, can undeniably improve the speed and accuracy with which the police apprehend criminals.
Detective Jon Rhodes (personal communication, 30th January, 2004), a Portland Homicide Detective, plainly states that genetic fingerprinting “helps us solve cases we likely might not be able to solve (otherwise)”. Genetic Fingerprinting is clearly a great leap forward in placing a suspect at a crime scene, but some disturbing problems are surfacing as we use this technology. In this paper I will explore some of the implications of using Genetic Fingerprinting as it has become commonplace in police work. I will illustrate the problems that have surfaced and discuss some measures that may help solve them.
Up until now, police have used methods of blood and protein typing, footprints, drug and firearm matching and eyewitness identification to place a suspect at the scene of a crime. Genetic fingerprinting technology has been applied to evidence from many crime scenes and the results have often shown previous technology to be frighteningly unreliable. In a study of 28 cases commissioned by the National Institute of Justice (Conners, Lundregan, Miller, McEwan, 1996) in which innocent people were convicted, some of the aforementioned identification techniques were used and later proved inaccurate. (See Fig 1).
In these cases, innocent people served an average of seven years in prison for crimes they did not commit. It is pertinent to note that four of the cases hung on the testimony of serology “expert” Fred Zain who was later discredited and charged with perjury. This highlights one of the responsibilities Genetic Fingerprinting has uncovered: that we need to figure out why people were wrongly convicted in the first place and prevent it from happening again.
The need for quality control. The science of genetic fingerprinting particularly lends itself cases like that of Nicholas Yarris, the man who was exonerated in paragraph one, as it deals with the probability that two samples came from the same person. 100% definitive results are only possible for a mismatch. The range of probabilities can be greatly altered by the kind of testing done. For example, when using STR (short tandem repeat) tests, which are used in Oregon police work (Rhodes, 2004), experts cite one-in-billions odds that the test samples came from the same person.
This is achieved by testing nine separate sites on the chromosome. Other tests that take into account only three sites broaden the odds to 2000 to one (Grand, 2002 p.2288). Considering the potential for similar DNA types to be found in the same area due to racial or family genetic similarities, the certainty with which genetic fingerprinting points to a suspect is far weaker in the latter example (Bowen, 1996).
Tests are therefore more or less reliable according to the testing lab’s standard procedures for a match. It may be wise to create international guidelines for admissible testing and a way to check that they are being followed. In a court of law it would be hard to argue with a genetic match of one-in-a-billon, but only provided that laboratory procedures and interpretation of the results are carried out correctly.
Unfortunately, this is not always the case. As recently as March 2003 the Houston Police Department forensics lab was exposed for turning out incorrect DNA evidence due to poor working methods and misinterpretation of the findings. UCI Professor William C. Thompson, a leading expert in DNA, was asked to investigate the laboratory. He found lax standards of controls and documentation, which increased the chance of incorrect findings. He also found the lab’s results were at times inconsistent with his interpretation of the tests. He concluded that police scientists, may have been distorting the evidence in their determination to close cases (UCI Professor Finds DNA Laboratory Errors That Sent Wrong Man to Prison, n.d.).
Considering genetic fingerprinting’s potential, scientific evidence can cause a heightened sense of trust in juries of the scientific findings (Conners, et al 1996, p xiii). As we continue to use DNA evidence in light of these kinds of mistakes, it becomes clear that laboratories should be subject to quality control checks by a regulatory body. It would also be a good idea for it to become common procedure for testing to be carried out at more than one certified laboratory to ensure correct interpretation of the results and prevent unthinkable mistakes.
Database Privacy Issues In Lafayette, Louisiana, law enforcement officers have solved 20% of unknown rape cases simply by working through their database of convicted criminals’ DNA and at this point they still have two thirds of the prisoners untested (Billiot, 2003). This is an excellent argument for collecting genetic information from felons. It frees police resources and increases the efficiency of the justice system. Is it justification, though, for taking swabs from every suspect in a case and then keeping that information on file when the suspect has been cleared?