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DNA Testing

DNA testing has become a popular tool to use in court when it comes to proving one’s innocence or guilt. The case Brim v. State, divided DNA analysis into two prongs, the first being creating the data for the analysis and the other being the actual statistical analysis of the DNA (Cogdell, 2011). The first prong gives the ability to exclude a suspect (Cogdell, 2011). The second prong determines how likely it is that the sample of DNA came from this suspect (Cogdell, 2011). Although DNA evidence seems very reliable, there is no national standards for determining what makes the DNA a match (Cogdell, 2011). There are many ways that DNA evidence can lead to a wrongful conviction.

Low Copy Number DNA

ow copy number DNA is when there is a small amount of DNA in a sample (Cogdell, 2011). If any sample of DNA is less than 200-300 picograms they are considered to be a low copy number (Cogdell, 2011). When this occurs, Polymerase Chain Reaction (PCR) is used to enlarge the samples so that there is enough to be used for a test (Cogdell, 2011). This is an issue because there is a greater risk of contamination (Cogdell, 2011). Although it can be a good way to look at DNA it is easily contaminated, which would make the DNA unreliable.

Matching Alleles and Loci Minimums 

 When looking at DNA, agencies look at thirteen specific places (loci), which are the characteristics that make up a person’s DNA profile (Cogdell, 2011). A DNA match can happen at any point in the thirteen loci, and as more loci match the DNA sample, the possibility that the DNA came from the suspect increases (Cogdell, 2011).  This is used to show that DNA matches can be linked to the suspect and the victim, and that should be explained to the jury (Cogdell, 2011). Hearing that there is a match can be confusing because of the idea of a match sounds as if the suspect committed the crime when in reality, if there are not as many matching loci, it is not as reliable.

False Positives 

When a person matches with a DNA sample, they are included as a possible suspect, so it is possible for someone who has been falsely accused to match the DNA, which especially happens when DNA testing is done to only a few loci (Cogdell, 2011). When only a few loci are tested, it is important that the jury knows of the possible issues that brings (Cogdell, 2011). This also is a problem when lab technicians determine the results to be a match, even when they are not (Cogdell, 2011). Again, it is important to understand how many loci receive matches. 

Crime Lab Errors 

There are a number of different ways in which a lab technician can commit misconduct. Looking at Fred Zain, who was a serologist in the Division of Public Safety Serology Division of West Virginia State Police Crime Lab, we see a number of ways he committed misconduct in the lab (Cogdell, 2011). The misconduct included (Cogdell, 2011):

  • Overestimating the results strength

  • Overstating the occurrences of genetic matches on evidence

  • Stating that multiple items were tested when only one item was tested

  • Reporting inconclusive results as conclusive

  • Altering lab records

  • Not reporting conflicting results

  • Not engaging in further testing to settle any conflicting results

  • Determining that a match has been made with the suspect when in reality it was only matched to the victim

  • Concluding scientifically impossible results

This type of misconduct was also found in labs in various states such as: North Carolina, Washington, Pennsylvania, Nevada and California (Cogdell, 2011).

It is important to understand the way that DNA could lead to a wrongful conviction because people typically think of it as way to prove innocence, but it in fact, can be easily misused and result in an incorrect outcome.

Techniques Used Today

DNA testing, although flawed, has led to hundreds of exonerations since 1989. Today, scientists use polymerase chain reactions (PCR) as a way to look at DNA (McGlynn, 2019). This PCR technique can further be broken down into two additional techniques: Short Tandem Repeat (STR) and mitochondrial DNA (mtDNA) typing (McGlynn, 2019). The STR method is used to access the DNA profile from almost all types of biological samples (McGlynn, 2019). The mtDNA method is used to evaluate evidence that is too broken down for STR (McGlynn, 2019). 

DNA Index System

In 1994, the United States Congress passed the DNA Identification Act (or the DNA Act) which includes the Combined DNA Index System (CODIS) that was created in 1990 (McGlynn, 2019). This gave the FBI permission to create a national DNA database (McGlynn, 2019). This database includes known-offender DNA profiles and unknown-DNA profiles that were collected through crime scene evidence (McGlynn, 2019). Although this database is accessible to law enforcement, pre-trial defendants and post-conviction litigants do not (McGlynn, 2019). Having a national DNA data base available only to the prosecution is not a fair way to ensure that the person convicted is innocent or guilty. Another problem with the reliability of a DNA database came into play with the 1998 National DNA Index System (NDIS). NDIS is a part of CODIS, and it includes federal and state and local forensic labs contributing DNA profiles (McGlynn, 2019). Post-conviction litigants can only use this tool if a database administrator, a court or a statue allows them access to do so (McGlynn, 2019). This is something that should not be so difficult to do for a post-conviction litigant, it should be accessible to ensure all of the evidence is reliable. Also, with law enforcement agencies as the ones who maintain this data base, it is possible that corruption could occur.

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