RALEIGH, N.C. — The North Carolina State Bureau of Investigation says it is finally catching up on cold cases. DNA is helping agents track down suspects, in some cases, years after crimes were reported.

Since WRAL's investigation of DNA testing three years ago, changes at the SBI crime lab have paid off, agents say. New equipment and new agents helped transform the productivity of DNA testing. Evidence from more than 6,000 rape cases that sat on local police department shelves for years are cleared and now being analyzed, the SBI says.

Since January of last year, the SBI tallied 145 DNA matches, or "hits," to suspects -- far more than the previous 11 years combined.

"We're taking cases that no one has any idea who may have done it, and we're able to tell them that, and it's made a world of difference in the morale of our unit," SBI Special Agent Chris Parker says.

But success breeds new challenges. Now, the lab cannot keep up with the DNA analysis and computer entry of felons. There is a current backlog of nearly 40,000 samples from crimes waiting to be solved.

"Every time we upload 2,000 of 3,000 samples, we're able to solve anywhere from five to seven or eight hits," Parker said.

The SBI estimates entering 40,000 new DNA samples into the database could yield 60 or 70 hits to cold cases.

By law, all convicted felons must submit DNA to the state's database.

"Obviously the larger your database is, the more success you're going to have," Parker said.

Another challenge may also lie ahead for the team of agents at the lab.

Legislative leaders left out requested DNA analysts in the state budget. North Carolina Attorney General Roy Cooper says public safety is at risk if they have to stop their work.

"If we don't get these samples into the database quickly, then there could be a rapist walking the street or a murderer walking the street."