How DNA Evidence is Used in Criminal Cases
One of the more recent technological advancements in the criminal justice world is DNA analysis. More and more frequently, especially in Texas, DNA evidence gathered from a crime scene is used to identify someone who may have been present. It is also used to exclude someone from consideration as a suspect or to save him or her from a wrongful conviction. Depending on how DNA evidence is used, the results can help or hurt a criminal case, so let’s dig a little deeper into the issues surrounding DNA evidence trial results.
DNA Evidence in Criminal Cases
DNA stands for deoxyribonucleic acid, and DNA is present in almost every cell of the human body. An individual’s DNA is the same in many types of cells, such as saliva, blood, skin tissue, hair and bone, and one’s DNA does not change over time. DNA is valuable in criminal investigations because no one has the same DNA, except for identical twins.
Because one’s DNA profile is unique for almost all people, DNA collected from a crime scene or victim can be compared to the DNA of a suspect to see if it matches. In the case of an alleged sex crime, for example, DNA can be gathered from hair, blood, skin cells or semen left on the alleged victim or at the alleged crime scene.
This evidence may be used to place a suspect at the scene if the DNA profiles match. If the DNA collected does not match the suspect’s DNA profile, that evidence can be used to exclude the individual. In cases where the DNA does not match that of any suspect, the DNA information may be entered into a DNA database to see if it comes up with a match.
How the DNA Database is Used in Criminal Cases in Texas
The FBI has a large database of DNA samples, called CODIS, and this database – as well as a growing Texas database – has been used innumerable times in Texas criminal cases. According to the Associated Press, the federal database was created in 1996, and Texas had an average of 200 DNA profile matches from that database each year in its first five years. In the following decade, the number of matches increased to a yearly average of 1,000.
In Texas, DNA samples are collected from people convicted of certain felonies, including some sex offenses. Over the years, the Texas DNA database has grown to more than 660,000 samples.
The San Antonio Express-News reports that at least 643 Texas homicide cases have been solved with assistance from the databases. In addition, the Innocence Project of Texas reports that 48 individuals have been exonerated by DNA evidence after they were wrongfully convicted and imprisoned.
In 2001, a new law improved access to DNA evidence after a conviction, and it has helped many people use DNA testing to prove their innocence. Dallas County has the highest number of DNA exonerations thus far, with 24 total. In comparison, Harris County has the next highest number with 8 DNA exonerations.
DNA analysis can be a powerful tool, but it is not the only evidence used in criminal cases. Further, the presence of an individual’s DNA does not automatically mean the individual is guilty of the charged crime. If you have been charged with a sex offense or other crime in Texas, contact an experienced criminal defense attorney to begin defending your case.