Defending Against DNA Evidence


Practicing  Criminal Lawyers in Broward and  must be familiar with DNA forensic issues. DNA Profiles Deoxyribonucleic acid (DNA) is a complex molecule found in the nucleus of each human cell. It carries a person’s genetic information. The components of the DNA molecule are arranged differently for every individual except between identical twins. A scientific process for analyzing DNA produces a print or profile that contains a pattern of bands believed to be unique to a particular person’s DNA. Criminal courts are seeing more DNA cases every year as forensic technology improves.

Utilizing DNA testing in Broward County courthouse crime lab, located in Fort Lauderdale, Florida, involves three steps: (1) creating a DNA profile of a sample; (2) determining whether the profiles of different samples match; and (3) if the samples match, computing the probability of a random match. Expert witnesses are required to offer statistical analysis of population frequencies and to assess the significance of a particular test result.

Many jurisdictions have statutes requiring convicted felons to furnish a blood sample for DNA printing; such prints are then stored in a data bank for future law enforcement purposes. The courts have generally upheld the admission of a DNA profile comparison to prove or disprove identity.

“HLA Blood Tests”

The results of a Human Leukocyte Antigen (HLA) blood test are often introduced in rape and incest prosecutions. Although such evidence does not by itself establish identity or guilt beyond a reasonable doubt, evidence of population percentages of certain combinations of blood characteristics is relevant evidence tending to establish the identity of the perpetrator of the crime.

DNA’s Role According to Florida Sex Crimes Attorney James Weick

The Urban Institute on Using DNA to Overturn Wrongful Convictions.

The researchers sorted the DNA test results into four categories:

Indeterminate — DNA testing could not determine whether the convicted person was the source of the DNA on the evidence.
Inculpatory — DNA testing confirmed that the person convicted was the source of the DNA.
Exculpatory but insufficient to support exoneration — DNA testing eliminated the convicted person as the source of the DNA, but elimination was not sufficient to support potential exoneration without additional probative evidence.
Exculpatory and supportive of exoneration — DNA testing eliminated the convicted person as the source of the DNA, and that elimination supported potential exoneration.

For a variety of reasons — including the age of the biological evidence — DNA testing in two-thirds of the cases yielded “indeterminate” results, meaning that DNA testing was not sufficient to determine whether the convicted person was the source of the DNA.

For more information about how DNA evidence may impact your case, contact William Moore Offices in Fort Lauderdale.