What You Need to Know About DNA Evidence

By Offices of Howard J. Wise  Jul. 11, 2011 11:30a

What is DNA and how can it be linked to you?

We hear about DNA evidence all the time. It's talked about in television shows, on the radio and in newspapers, but how many of us really know what it is and how it can be used against you? "DNA" or deoxyribonucleic acid is the fundamental building block for a person's entire genetic makeup. It's the blue print passed on to you from your parents.

DNA remains the same throughout your lifetime. It can be found in saliva, blood, hair, skin tissue, sweat, bone, urine, semen and earwax. With the exception of identical twins, no two people have the same DNA make-up. Therefore, it can be a powerful tool for investigating crimes. It can link a suspect to a crime and also identify a victim.

The most common forms of DNA evidence collected at a crime scene are saliva, blood, skin tissue, hair and semen. DNA can be crucial to a sexual assault or other violent crime case. DNA evidence left on the body of a victim can be compared with known DNA samples already entered into the FBI's database called, "CODIS," Combined DNA Index System. This system allows local authorities to compare DNA profiles with known DNA profiles across the country.

This system can help identify suspects in a crime. If you have been accused of a crime, we strongly recommend that you let a Chicago criminal defense lawyer from the law offices of Howard J. Wise and Associates explain everything you need to know about your rights when it comes to police evidence and DNA.

DNA Evidence: Explaining Contamination and Results

Proper collection of DNA evidence at a crime scene is crucial to the preservation of the evidence as it can easily become contaminated or degraded. The sloppy work of some law enforcement and lab technicians has been known to contaminate DNA evidence. All it takes is for a person to sneeze or cough on the evidence or the person collecting the evidence to touch his/her mouth, nose, hair or body and then touch the evidence for it to become contaminated.

Environmental factors such as heat and humidity can also contribute to the degradation of the evidence. DNA evidence should be packaged in paper, properly labeled with a proper chain of custody, handled by someone who is wearing plastic gloves and testing should be completed with clean instruments.

There are three types of results in DNA evidence:

• Inclusion - This is when a DNA profile of a known individual matches the DNA profile collected from crime scene evidence, the person is "included." This does not necessarily mean you are guilty.
• Exclusion - When the profile from the individual does not match the DNA profile generated from crime scene evidence, the person is "excluded." This does not mean you are innocent. 
• Inconclusive results - This means the DNA testing did not produce information that allowed the individual to be included or excluded. This can occur if not enough DNA evidence was collected, or if more than one persons DNA was mixed with the sample. 

An experienced criminal defense attorney, like those with our firm can assist you in preparing a strong defense if you have been linked to a crime through DNA evidence.

Who is required to provide a DNA sample in Illinois?

Every state has DNA database laws that define which convicted offenders must enter profiles into its database.  In Illinois, there are over 398,000 DNA profiles from convicted offenders. All 50 states require sex offenders to provide DNA samples. As of 2010, Illinois requires all convicted felons to submit DNA samples, as well as some juvenile offenders, some individuals convicted of misdemeanors and those held under civil commitment laws, including those who are mentally ill, but found guilty of sex crimes.  Contact a Chicago criminal defense attorney right away if you have been arrested and asked to submit DNA evidence.  Howard J. Wise and Associates can help provide expert legal help to protect your rights.   

Contact a Chicago criminal defense attorney from our firm immediately to find out your rights regarding DNA evidence.