What is DNA evidence?

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Deoxyribonucleic acid (DNA) evidence is commonly used by any criminal defense lawyer who can use it to support their client’s case. DNA is not always present at a crime scene, at least not in terms of being helpful in defending an innocent person charged with a crime they did not commit. An individual’s “genes” are encoded in their DNA. It can be collected from skin cells, hair, blood, and other natural substances from the body. Everyone’s DNA sequencing is unique from everyone else’s, except for those persons who are identical twins. As your criminal defense lawyer might tell you, DNA testing can be used to resolve crimes that occurred even before DNA testing was available. This has led to the exoneration of many people who were convicted of crimes they did not commit.

The History of Using DNA Testing to Solve Crimes

A British scientist by the name of Alec Jeffreys developed the science of DNA testing in 1985. It first became invaluable a year later when it was used to help solve a double homicide. DNA evidence had been collected from unsolved murder and rape cases which led to convicting the perpetrator in 1987. Since then, U.S. law enforcement agencies at the local, state, and federal levels have steadily added to DNA databases for ease of identifying suspects. In addition, sex offenders within the U.S. are required to submit samples of their DNA to their local police department. This does not guarantee that their samples are processed in a timely manner, however. This may present a challenge to a criminal defense lawyer who is building a defense case for their client and wishes to identify the real perpetrator of the crime.

What is the process for testing DNA?

The process for identifying, testing, and submitting the results to court will vary somewhat from case to case based on the unique circumstances of the crime. Your criminal defense lawyer can explain how the process will work in your case. Generally speaking, you can expect it to more or less follow these steps:

  1. The DNA material will be collected from one or more biological sources from the crime scene. This might come from any of the following if they are present:
  2. Hair
  3. Blood
  4. Skin cells
  5. Semen
  6. Vaginal secretions
  7. The DNA evidence may be analyzed and tested using the polymerase chain reaction method. Even if there is very little DNA material available, this method can still be used. It can then be checked against known profiles in existing DNA databases submitted by previous suspects.
  8. DNA tests are more than 99 percent accurate. Because there is only one in a billion chances that the DNA analysis is incorrect, when there is a match between DNA at a crime scene and the known DNA profile of a suspect, it can be critical for clearing the name of an innocent person.

Legal Representation Can Make a Difference

If you are in need of quality legal representation from a law firm with a successful record, a criminal lawyer Bloomington, IL trusts can provide the guidance you need.



Thank you to our friends and contributors at Pioletti & Pioletti for their insight into criminal defense and DNA evidence.