DNA Evidence A Powerful Technology

DNA evidence is used to investigate and prosecute crimes like rape or murder.

"It's a positive ID that a person was there. It shows they were present at the scene or had contact with the victim at some point. It's used quite often and required in investigations of sex crimes and violent crimes," District Attorney Cono Caranna said.

Such evidence can also work in favor of the defense, by excluding suspects in a case. It's also used to prove paternity, and in divorces to prove infidelity. But Attorney Earl Denham says many defense attorneys are actually intimidated by the technology.

"Probably only ten to 15 percent of defense attorneys ever look back behind the DNA report in order to look at the types of testing that are done in an attempt to see whether or not the results are true results."

Denham says there are several reasons why the results may not be foolproof.

"The DNA results are subject to pollution. It's not uncommon to have DNA from two sources that come in the same and it's not uncommon for DNA testing to come back without a perfect match."

The tests are expensive too; up to a thousand dollars for each sample. But geneticist Dr. Wesley Burkhardt says the results are certainly worth the costs.

"It's extremely powerful, I mean the U.S. Government uses this in identifying remains of servicemen so obviously it's a very important tool and it can give a lot of investigative leads to individuals," Burkhardt said.

Leads that can either send a guilty person to jail, or clear someone who has been falsely accused of a crime.