The 14-year-old was last seen at a high school party in a woods near her home in Woburn MA and then she vanished without trace.
But 22-years on P.I Michael Garrigan, who has worked the case from the very beginning says he has "credible leads" which could see people in the woods that night prosecuted.
He told Fox 25: "I developed some leads over the past year, we can’t discuss those at this time, but very credible leads from several sources.”
And with the help of trained cadaver dogs he hopes he's hoping to confirm that traces of human decomposition in the woods, which he believes hold the key to discovering the truth.
It's not the first time that investigators have returned to the woods. Detectives launched a revitalized search in 2009, just before what would have been Melanie’s 35th birthday.
While Melanie’s parents have passed on, her aunts and other family members are standing watch over the new search.
Garrigan says he can’t share many details on the investigation, but says he believes the people he hopes will ultimately be prosecuted were absolutely in the woods on that October night.