BOSTON (CBS) – The disappearance and murder of Molly Bish has frustrated and worried investigators for the past 12 years. The 16-year-old’s killer has never been found. Now WBZ has learned evidence from the crime scenes, such as cigarettes found at Warren’s Comins Pond where Molly disappeared, is being tested for DNA.

District Attorney Joe Early is hoping recent advances in DNA testing will help solve the case. “We hope to get a break there,” says Early. “As we’ve said before, time can be your enemy right away but as years pass, time becomes your friend. There is a variety of emotions involved with this as opposed to other homicides. This one is unique, unique for so many reasons.”

Molly disappeared during her lifeguard shift on June 27, 2000. As the anniversary of her murder nears, investigators are making plans to head to Florida once again to interview convicted killer Rodney Stanger. They’re also trying to talk with Gerald Battistoni, a convicted child rapist. Both men are extremely violent, have ties to the Warren area, and resemble the sketch of the man Magi Bish saw at the pond the day before Molly was killed.

WBZ-TV’s Beth Germano has reaction from Magi Bish

When he’s asked how confident he was that investigators would find Molly’s killer, Early replied, “That’s an interesting question. I’m confident in the ability for State Police to do the work they need to do. Again I think we need a break or two but we will never give up. We’re going to pursue Molly’s killer as long as I’m in office and after that.”

Twenty pieces of evidence will be tested for DNA. Some have been tested in the past but not all. The Worcester County District Attorney has also sent off official requests to the FBI to have them help in the search for Molly’s killer.