By Bree Sison, WBZ-TV

WOBURN (CBS)- Volunteer private detectives say a search in Woburn is the best chance they’ve had in years of finding Melanie Melanson.

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The 14-year-old disappeared in 1989 after a night of partying in the woods with friends about a half-mile away from the search site.

“This is the most indication of human remains that we’ve had,” said Alan Tate, co-founder of Mission for the Missing.

Tate and his organization have helped Melanson’s family coordinate a dig that expands on previous searches by Woburn and State Police. Last November three cadaver dogs alerted them to the area. Soil samples there tested positive for human decomposition fluids.

With the permission of law enforcement, Mission for the Missing is back to dig up a bigger area.

“Woburn Police have done a number of digs over the years. They’ve worked their way up to this area,” said Tate.

Joining the efforts this week are K-9 units from Connecticut Canine Search and Rescue. On Friday, dogs that are new to the case alerted to the same area as the previous teams.

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Dr. Ann Marie Mires of Forensic Archaeology Recovery (FAR) is supervising the dig. She says her team of four archaeologists and anthropologists are looking for changes in soil color and composition as an indication that remains are nearby.

“If we were to find anything we would have to turn it into a crime scene. Right now it’s an inquiry,” said Dr. Mires.

No one has ever been charged in the Melanson case, though investigators have long suspected two men who were with her the night she vanished could be responsible. Woburn Police were on scene Friday to supervise but wouldn’t comment on the official criminal investigation.

“If we have a credible lead, we will certainly follow address that,” said Chief Robert Ferullo, who was a patrolman when Melanie disappeared.

Ferullo says they welcome the help from the private groups.

“We’re a small town where everybody knows everybody and this is very important to us,” Ferullo said.

Melanie’s parents died years ago. Her extended family has kept the search efforts going, raising $15,000 to help pay for the private dig. When word got out that they would look again in Woburn, the family’s private investigator received tips to search an area in Stoneham.

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Last month dogs indicated there could be something in Stoneham, so volunteers say they will look there next, should the Woburn search be met with negative results.