BILOXI, MS (WLOX) - It's a genetic fingerprint that can send criminals to prison or set free someone who's been wrongly accused.
Pascagoula police used a DNA match this week to arrest a suspect in a nearly two decade old rape case.
A Mississippi law passed in 2007 requires all Department of Corrections prisoners to give a cheek swab sample of their DNA. Those samples are entered into a database and can be checked against DNA evidence gathered at crime scenes.
That's what led Pascagoula police to arrest Lester Selmon this week and charge him with a rape that happened 19 years ago.
Selmon gave the DNA sample as he was leaving prison last year after serving time for another sexual assault.
"The advances of science now, it's just amazing as to what we can do, what makes our jobs a lot easier," said Captain Shannon Broom with Pascagoula Police.
Those advances in DNA technology led Pascagoula police to 47-year-old Lester Selmon, who was arrested Wednesday and charged with raping a 15-year-old girl, in her own bed, 19 years ago.
"We were able to contact the state crime lab who actually had maintained some samples that were taken from the sexual assault kit back in 1990," said Broom.
DNA taken from that 1990 evidence produced a match with the swab sample Selmon gave when he was released from prison after serving time for a 1995 kidnapping and sexual assault in Biloxi.
"Well, it's an absolute identifier. It collaborates the fact that the person was there. And depending what the sample is, what was going on," said Harrison County District Attorney Cono Caranna.
In his nearly 24 years as Harrison County District Attorney, Cono Caranna has seen DNA technology play a more critical role in prosecuting criminals.
"Just having DNA doesn't have anything unless you have something to compare it with. And since 2007, the crime lab has been taking cheek swabs on people they're releasing from prison. That's going to give a great expansion of the database we have to compare things to," said the district attorney.
While DNA can certainly be a powerful tool for identifying and convicting criminals, that same technology can also be used to clear someone's name when they're not the guilty party.
"We've had folks that have been wrongly accused that have been released from prison because of DNA, that spent many years of their life locked up, because they were wrongly accused. And DNA has cleared them of that," Broom said.
"It's not just a tool for prosecutors. It's a safeguard for innocent folks and it's really bad news for a criminal," Caranna said.
In a recent ruling, the U.S. Supreme Court said that DNA possesses a unique ability to convict the guilty and free the innocent. However, in a 5-to-4 decision the high court ruled that prisoners do not have a constitutional right to demand DNA testing of evidence that remains in police files.
The court's conservative bloc agreed to let states work out the rules for new testing of old crime samples.