We’ve all seen how DNA evidence can save the day on television or in a novel, but how does it work in real life? Although it doesn’t always save the day, the ability to gather, analyze, and match DNA evidence has certainly changed the criminal justice system in a notable way. The science behind DNA profiling is extremely complicated; however, a Murfreesboro criminal defense lawyer explains the basics of how DNA is gathered and used in a criminal prosecution.
What Is DNA?
The acronym “DNA” is short for deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information for those living organisms, including humans. Your DNA can be found in blood, semen, saliva, urine, feces, hair, teeth, bone, tissue, and cells. Although 99.9 percent of human DNA sequences share the same in every person, enough of the DNA is different that it is possible to distinguish one individual from another, unless they are monozygotic (“identical”) twins.
How Is DNA Evidence Collected at a Crime Scene?
When a crime has been committed, the job of the responding law enforcement agency is to figure out and/or apprehend the perpetrator of the crime. The prosecuting attorney’s job is to bring the suspect to trial and secure a guilty verdict. To do that, the prosecutor needs evidence that the suspect did, in fact, commit the crime in question. A police offer might come across all different types of evidence during a search and seizure, including opportunities to collect DNA evidence. DNA might be extracted from common items such as clothing, weapons, glasses or bottles, a hairbrush, or a cigarette butt. If a person touched an object or weapon, skin cells may have been left behind. This low-level DNA is sometimes referred to as “touch DNA”. It can even be collected from a victim’s skin or bruises where they were handled roughly. Low-level DNA samples may be helpful when examining evidence where it would be difficult to retrieve fingerprints—such as textured surfaces on gun handles or automobile dashboards.
Using DNA Evidence to Help Solve a Crime
DNA left behind at a crime scene can only help if compared to a suspect’s DNA. To compare the victim’s or suspect’s DNA profile to the recovered crime-scene DNA, the laboratory will need to have their known biological samples available for a side-by-side comparison. These known samples are called reference samples. In some jurisdictions, a DNA sample is routinely taken from an arrestee during the process of booking and fingerprinting. The United States maintains the largest DNA database, with the Combined DNA Index System (CODIS) holding over 9 million records as of 2011. When DNA evidence is uncovered as part of a criminal investigation it will be run through CODIS to check for a match. Sometimes people close to the investigation will also be asked to voluntarily provide a DNA sample to exclude them as a suspect, or in the hope of finding the perpetrator. Because taking a DNA sample has long been considered a “search and seizure” by the courts, the police cannot force you to give a DNA sample unless the officer has first obtained a warrant signed by a judge.
How Accurate Is DNA Evidence?
The accuracy of DNA evidence depends, in large part, on how carefully it is handled and which procedures are used compare the samples. Given the odds of anyone else in the entire world having your exact DNA are astronomical, unless you have a twin, it can be an excellent criminal investigation tool. When carefully handled it can be used to place a suspect at the scene of a crime. Of course, mistakes are made in the handling of DNA evidence which is why you need an experienced criminal defense attorney on your side if the State plans to use DNA evidence against you in a criminal prosecution.
Contact a Murfreesboro Criminal Defense Lawyer
If you have been accused of a criminal offense in the State of Tennessee, it is in your best interest to consult with an experienced Tennessee criminal defense lawyer at Bennett, Michael & Hornsby as soon as possible to ensure that your rights are protected. Contact the team today by calling 615-898-1560 to schedule your appointment.