A break in a murder mystery, all thanks to DNA. That's how police caught a man they say is involved in the 2002 Troy murder of a young couple. Prosecutors were set to try two men in the case until the DNA of a third man was matched to the crime scene. Now, criminal justice advocates want to pass a law to expand the database that police used to catch him. DNA upon arrest is already a federal law. Currently, New York State has in place a law that requires some people convicted of a crime to submit DNA, but the governor's proposed bill would require anyone convicted of a crime to submit a DNA sample. Our Sabina Kuriakose has more on why prosecutors say that if this law was in place earlier, it could have made a difference in this case.

  To view our videos, you need to
enable JavaScript. Learn how.
install Adobe Flash 9 or above. Install now.

Then come back here and refresh the page.

"When you have these kinds of developments in a case, it can dramatically affect people's lives, " said Rensselaer County District Attorney Richard McNally.

More than eight years later, there's been a new development. A hit on the DNA of 40-year-old Michael Mosley, a man who was never considered a suspect in the case. It's all thanks to a state database that collected his DNA after an assault conviction. It wasn't Mosley's first run in with the law, but under a 2006 law, it was the first time he had to submit a DNA sample.

"Criminals don't specialize. So the guy who might have committed a rape and murder that's currently unsolved, will also steal something out of the Minimart," said Mary Kavaney, Deputy Secretary of Public Safety.

So the state Division of Criminal Justice Services is partnering with the Governor on a proposal to expand that database to anyone convicted of a felony or misdemeanor. Right now, only some crimes are covered.

"It's a crime prevention tool as well as a crime solving tool, and an exoneration tool as well," said Kavaney.

That's exactly what attorney Trey Smith is hoping for. The DNA match to Mosley was discovered days before his client - Terrence Battiste, one of two defendants in the case - was set to go on trial. No DNA links them to the case.

"It's very difficult to undo a conviction once it's done. So Terry Battiste and Brian Berry are very fortunate that this evidence has come out," he said.

Yet Smith cautions against any unchecked expansion of the database.

"I think we should all be concerned anytime the police and the state engage in dragnet collection of evidence," he added.

Still, prosecutors like McNally back the bill, citing this case as an example.

"It's another tool in the police toolbox to do the right thing," said McNally.

The New York Civil Liberties Union opposes expanding the state DNA database. It contends that there's just too much room for human error when it comes to the handling of DNA samples.

Michael Mosley remains in Rensselaer County Jail. Cases are pending against Terrence Battiste and Brian Berry.