Forensic DNA Analysis

However, while federal money can provide dollars to buy equipment, train technicians and build laboratories, it is not the total answer to solving the problem. As forensic DNA analysis science matured there also developed a need for standardized testing protocols, control samples, quality control practices and measurements to ensure that analysis of forensic DNA analysis was reliable in all jurisdictions. This is critical because the outcome of a DNA analysis may determine whether a suspect lives or dies, or spends the rest of their life in prison.

A primary goal for all laboratories has been to decrease their turnaround time for sample analysis. Turnaround time (TAT) is defined as the amount of time required from the time of sample receipt at the laboratory to the time a final report is provided to the requesting department. TAT will vary from lab to lab and also from sample to sample. Labs which are highly automated with robotic analysis equipment can process samples faster than those using manual methods. Different types of analysis require different times to perform. Often test results are inconclusive and must be repeated to more provide a definitive answer. Repeat testing not only adds to the time required to get the results for the test sample in question, but also to the overall backlog of the lab. As an example of how sample load affects TAT, take for example a simple cheek swab taken from a suspect. Two independent samples are taken from the suspect. One sample is placed in an archive storage as a "backup sample." The other sample is extracted In the lab and then, at a minimum, each sample is analyzed in duplicate. So the sample from a single suspect actually produces two analyses. It you have 10 individuals that must be screened, the analysis load quickly rises to 20. Since each lab has a fixed capacity to analyze samples, it is obvious how the backlog is created.

New Technology and Analysis Methods

The introduction of newer analytical technology has led to faster and more definitive analysis. The introduction of the Short Tandem Repeat (STR) test procedure has allowed for more reliable analysis on samples which previously were too small or too degraded to analyze. The CODIS database works on the recognition of 13 specific STR loci. The development of highly automated equipment to facilitate handling of large number of samples has greatly increased the number of samples that can be analyzed. Many larger labs have gone to automated robotic equipment that handles many of the manual operations that technicians routinely performed in the past.

The introduction of fluorescent tags, gas chromatography and now mass spectroscopy equipment to the DNA analysis arsenal has added a new dimension to forensic DNA analysis. However, due to the sizable cost of this equipment, only large labs like the FBI, major commercial laboratories,sState and some major large city labs will be able to have this type analysis available. Small departments will not be able to develop these methods because they cannot afford the costly equipment, nor will they be able to afford the technicians to run them. Thus, the backlog issue, while improving, will be with us for a long time.