Questioning the Technology Used to Read DNA Evidence

How many innocent people have faced wrongful convictions, how many guilty people have been exonerated due to the precarious manner in which DNA samples are collected from a crime scene and the way in which that possible DNA evidence is analyzed in a crime lab? It's said that the technology on which forensic scientists rely is still in its infancy; it appears to have been born prematurely.

What is DNA Evidence?

It might be better to first ask, "What is DNA?" DNA is the short name for deoxyribonucleic acid, an acid in which the genetic information or code of a cell is contained. This genetic code can roughly be thought of as a "blueprint" that describes the design of a unique life, an individual, for example. Every individual is genetically unique except for identical twins. It's logical to view DNA evidence as a powerful tool in a criminal justice system, but sometimes the same tools used to build can also be used to destroy.

The Problem With DNA Samples and DNA Analysis

DNA samples collected at crime scenes are often "mixed," meaning that they are the sample of two, three, four, or more people which complicates the far-from-perfect method of performing DNA analysis. Basically, a DNA profile consists of peaks or "spikes" known as "alleles" that occur or repeat in pairs at specific locations on a person's chromosomes. The pair of alleles (pair of peaks) are formed from a contribution from each parent and it is these peaks that are interpreted by forensic scientists.

There are several things that can go wrong with DNA analysis which determines what is DNA evidence and, consequently, possible wrongful convictions or the exoneration of a guilty suspect. Mixed DNA samples can cause more than two alleles or peaks to repeat at a specific location on the chromosomes. Determination of which peaks belong to which individual is left to the forensic scientist; and what if that scientist has been following the investigation of the crime for which he was given DNA samples? What if he or she has been made privy to the criminal background of the suspects from which samples were collected? What if he or she has been influenced by law enforcement officers who collected evidence? According to the article, "Fallible DNA Evidence Can Mean Prison or Freedom," by Linda Geddes, "...Much of the DNA analysis now conducted in crime labs can suffer from worrying subjectivity and bias." Ms. Geddes points out that, "...There are significant inconsistencies in the guidelines on how to interpret a sample."

Technology itself is another possible problem in DNA analysis because flaws in the computerized machines employed in the process of analysis can and have created false peaks (alleles) and can and have interfered with the presentation of real peaks. When the technology involved in electronics like digital cameras fail, it's usually not a big deal; but, when it is flawed and unreliable in DNA analysis that takes place in crime labs, it could result in wrongful convictions and the exoneration of a criminal. Is this technology being stretched too far?