LAS CRUCES, N.M. -- The Dona Ana County Sheriff's Department's evidence room is getting crowded while other items are being stored in semis.

But with better crime-fighting technology, and certain laws, individual pieces of evidence must be kept longer or indefinitely.

Evidence comes and goes in the department’s evidence room, but some things remain.

“Some of these cases are so old that I have to get a disposition to sign off on that and that's kind of on the back burner right now cause I have to deal with the new evidence that's coming in,” said Mary Jo Garcia, an evidence technician.

Some evidence like pictures are used daily in court, but because of appeals, many have to be kept.

Homicide and rape evidence is held forever due to the possibility of serial cases. Other items can't leave because deputies didn't sign off on them.

“Here's another from 1991. (She pulls a package down from a shelf) It's beer and I don't have a disposition. This deputy is no longer here,” Garcia said.

Today 19 bullet casings from an AK-47 drive by shooting were entered.

“We can't stop the evidence. Evidence is the most important part of the police investigation. As evidence is collected it piles up and pile us and piles up,” said Sgt. Joe Renaud of the Dona Ana County Sheriff’s Department

The county looks for a solution as it tries to follow one rule.

“One item comes in and one item gets destroyed or gets returned to the owner,” said Renaud.

Each year deputies do an inventory check to see if some things can be destroyed, but that doesn't guarantee it will move.

“At the rate that we're used to if we add another shelf in here that shelf will be filled in about 6 months,” said Renaud.

The department sells some of the larger evidence items it can get rid of on a Web site similar to eBay called propertyroom.com.