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Detail of DNA sampling tubes in Laboratorio forensic equipment.

Understanding DNA Used as Evidence

Madson Castello Law  Oct. 24, 2022

DNA can significantly affect the outcome of a criminal case. DNA could be the most valuable piece of evidence in your case when facing criminal charges—evidence provided by DNA can either connect you to the crime or prove your innocence. Given the role that DNA evidence plays in criminal cases, it is critical to understand how accurate and reliable DNA testing is and whether you can avoid a conviction if there was a DNA match in your case.  

At Madson Castello Law, our criminal defense attorneys leave no stone unturned when defending our clients in Dallas, Texas, and throughout North Texas. We are known for our history of success and relentless dedication to clients regardless of the nature of the allegations against them. Our skilled attorneys offer highly personalized representation to each client to help them achieve the best possible outcome.  

Collecting and Preserving DNA  

DNA, which stands for deoxyribonucleic acid, is a molecule that exists in every cell of the body and contains the individual’s unique genetic code. Each individual’s DNA is 99.9% identical from person to person. No two individuals have exactly the same DNA sequence, though. The only exception is identical twins.  

According to the Congressional Research Service (CRS), states began enacting laws requiring DNA collection from offenders convicted of certain crimes in the 1980s. DNA evidence can play a critical role in criminal investigations and prosecution. It can identify a perpetrator, prove innocence, or even result in a wrongful conviction. During a criminal investigation, forensic scientists perform a comprehensive analysis by comparing DNA collected at the crime scene to DNA samples taken from a suspect.  

DNA can be extracted from various sources, including blood, saliva, hair, teeth, and bones. Since DNA is a fragile molecule, there are strict procedures for collecting and preserving this type of evidence to ensure 100% accuracy in criminal investigations.  

Using DNA as Evidence  

DNA can be used as evidence in criminal cases in several ways depending on whether the suspect is identified or not:  

  • When a suspect is identified. The suspect’s DNA will be taken and compared to the DNA found at the crime scene. If there’s a match, the suspect may be prosecuted for the crime. 

  • When a suspect is not identified. The DNA found at the crime scene is taken to the lab and compared to profiles from a database of DNA profiles.  

The importance of DNA evidence during criminal trials cannot be overstated. However, it is also important to understand that DNA evidence can be used post-conviction. States provide mechanisms for convicted individuals to request DNA testing that may prove their innocence.  

If a person is facing criminal charges and there was DNA found at the crime scene or on a victim, DNA testing can be performed to prove their guilt or innocence. If you are facing charges and the police claim that your DNA was found at the crime scene, do not hesitate to speak with your attorney before you make any statements to law enforcement.   

How Effective and Accurate Is DNA Evidence?  

It is true that DNA testing has revolutionized the way criminal cases are investigated. DNA evidence has become a powerful tool in criminal prosecution. But how effective and accurate is DNA evidence?  

DNA testing is an effective and reliable way to identify or eliminate a suspect in a criminal case. However, DNA testing is not 100% accurate, which is why it may be possible to challenge DNA evidence to avoid a criminal conviction. Some of the factors that may cause a defense lawyer to challenge the accuracy of DNA evidence when defending a client include: 

  1. Contaminated sample. Crime scenes are not exactly the cleanest environments. Since DNA samples are found and collected at crime scenes, the risk of contamination should not be ruled out.  

  1. Improper lab procedures. Labs must follow strict guidelines when handling, storing, labeling, and analyzing DNA samples. Failure to follow proper procedures can yield inaccurate results.  

  1. No connection to the crime. A defendant’s DNA found at the crime scene does not directly connect that person to the crime in question. Thus, even if there is a match in DNA testing, it may still be possible to prove that you have no connection to the crime.  

If your DNA matches biological evidence found at the crime scene or on a victim, proving your innocence can be more difficult. However, it may still be possible to challenge biological evidence used in court. Contact a skilled criminal defense attorney to investigate your situation and determine if the prosecutor’s case lacks strength.  

How Can a Criminal Defense Attorney Help You Challenge DNA Evidence? 

Regardless of whether DNA evidence is the only evidence that supports the criminal charges against you, it may still be possible to challenge it with the help of an experienced criminal defense attorney.  

A defendant whose criminal charges are based on DNA evidence needs an attorney well-versed in the use of DNA evidence during criminal trials. They need someone to investigate the case and find weaknesses or holes in the state’s case against the defendant.  

Our criminal defense attorneys at Madson Castello Law have tried more than 300 cases to a jury and know what it takes to help clients avoid a conviction and prove their innocence by challenging DNA evidence alone. One of the most common ways to challenge DNA evidence is to highlight the errors in the handling, collection, or storage of DNA samples.  

Contact Madson Castello Law  

If you have been arrested for a crime and DNA evidence is used to support criminal charges against you, our attorneys at Madson Castello Law can fight for you. We have extensive experience helping defendants challenge DNA evidence and seek to avoid a conviction. We understand that time is of the essence when it comes to responding to criminal allegations. Reach out to our office in Dallas, Texas, to start working on your defense.


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