08/01/2012 07:19 EDT | Updated 12/06/2017 17:00 EST

Melanie Melanson Missing: Soil Samples, Cadaver Dogs Help Revive Cold Case

A team of forensic anthropologists is preparing to dig for evidence in the case of Melanie Jo Melanson, a missing Massachusetts teenager who disappeared almost 23 years ago. Melanson went to a party with friends and never returned.

According to Michael Garrigan, a private investigator who has worked on the case since 1991, soil samples that were taken from a specific area of interest in the case have tested positive for elements of human decomposition.

"I received intelligence that led me to the location as being a possible place for her burial," Garrigan told The Huffington Post. The private investigator did not disclose the location but said it is not far from Woburn, a city about 12 miles northwest of Boston.

"We recently set up a search with some cadaver dogs in the same area, and they also alerted," said Garrigan. "We now have a dig set up for Aug. 17 and 18."

Melanson, a freshman at Woburn High School, was just five days away from celebrating her 15th birthday when she attended an outdoor party on Oct. 27, 1989. The gathering, which was attended by about 20 people, took place in a wooded area along the Woburn-Stoneham line.

"People started to leave around 10:30 or 11:00 that night," Garrigan said. "It got down to just three people -- Melanie and two gentlemen -- and they came out of the woods and she did not."

The two men later told police they had left the party without Melanson. Local law enforcement conducted multiple searches of the area, but they were unable to locate any sign of the missing teen.

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Jessica Pastore, a spokeswoman for the Middlesex County district attorney's office, said authorities have not named the two men who were allegedly last seen with Melanson as suspects or persons of interest. She did, however, say that authorities do not think Melanson is alive.

"We presume that she is deceased," said Pastore.

Garrigan told HuffPost that Dr. William Marvin Bass, a renowned forensic anthropologist at the University of Tennessee-Knoxville, will lead the upcoming dig. He also said it will be conducted in collaboration with local law enforcement.

Neither of Melanson's parents will be present for the dig.

"They both died somewhat young," Garrigan said. "They were completely heartbroken, and [their daughter's disappearance] probably contributed to their early demise."

In a recent interview with Boston's WHDH-TV, Melanson’s uncle, Frank Mascuilli, said the missing teen's remaining family members are hoping for closure.

"We're just hoping we can get some answers ... beyond being able to explain it," Mascuilli said.

Garrigan, a father of four, said he has worked the case voluntarily almost from the start, contributing his time and money pro bono. He wants nothing more than to give Melanson a proper burial.

"I won't stop," Garrigan said. "It's not about the dollar, it's about the child, and right now we are closer than we've ever been."

Melanie Melanson was 5 feet 3 inches tall and 105 pounds at the time of her disappearance. She had blonde hair, blue eyes and braces on her teeth. A $5,000 reward is being offered for any information leading to her remains. Anyone with information is asked to contact the Woburn Police Department at 781-933-1212 x853 or the Massachusetts State Police at 781-897-6650. Visit "Find Melanie Melanson" on Facebook:!/melanie.melanson.5

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