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An old wallet belonging to a convicted killer who has long been a "person of interest" in the unsolved murder of a Massachusetts girl may be the break cops have sought for 12 years.

Molly Bish, 16, of Warren, Mass., disappeared in June 2000 from a local pond where she worked as a lifeguard. After the largest search for a missing person in Massachusetts history, Bish's remains were discovered three years later about five miles from her family's home.

Rodney Stanger, a 64-year-old native of Southbridge, Mass., who was living in the area at the time, emerged as a person of interest in 2009. Stanger, who abruptly moved to Florida following Bish's disappearance, is serving a 25-year prison term for the 2008 stabbing death of his live-in girlfriend, Chrystal Morrison, in Summerfield, Fla.

Fox affiliate WFXT-TV reported that Morrison's sister, Bonnie Kiernan, recently traveled to the Florida trailer home where the couple lived to retrieve items belonging to Morrison. While there, Kiernan found a wallet belonging to Stanger that was hidden inside a kitchen cabinet, according to the station. In it was a Massachusetts Firearms Identification Card, with a photo of Stanger that bears a striking resemblance to sketches made of a suspicious man seen hanging around the pond the day before Bish vanished. The F.I.D. card was renewed just two months before Bish's disappearance from Comins Pond in Warren.

"He looks just like the sketch," Kiernan told the Worcester Telegram & Gazette. "It's him. I have no doubt it's him."

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The wallet also held Stanger's birth certificate, which listed Warren, Mass., as his birthplace, as well as a Massachusetts fishing license and keys to a safety deposit box.

Stanger was already a person of interest in the Bish case, partly because of a tip from Kiernan. After Morrison's death in 2008, Kiernan told cops about a cryptic phone call from her sister, in which the doomed woman implied Stanger may have been involved in murders in Massachusetts, according to the Worcester newspaper. Morrison mentioned Bish and another girl, Holly Piirainen, who disappeared in 1993 in Sturbridge, a town adjacent to Southbridge. No one has ever been charged in the death of Piirainen, whose body was found two months after she disappeared by hunters in nearby Brimfield.

"I'm hopeful the state police will follow up with this," Bish's sister, Heather, told the newspaper. "We appreciate the people that come forward because it gives us a reason to push the investigation."

The Worcester district attorney, meanwhile, is planning to conduct DNA testing on several items, including discarded cigarettes from Comins Pond and combs found inside Stanger's Florida home, according to local reports.

"We hope to get a break there," Worcester District Attorney Joseph D. Early, Jr. told WBZ-TV last month. "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."

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