DNA testing has confirmed that unidentified remains in a pauper’s grave in Georgia belong to a 15-year-old Michigan boy who ran away from home after school nearly 40 years ago, authorities said.

Andrew Jackson Greer walked out of Addison High School in Lenawee County on Feb. 12, 1979, and simply never returned home, marking the start of a nearly four-decade mystery for relatives and friends in his hometown of Clayton.

But the cold case was finally solved after a forensic analyst from the Center of Human Identification at the University of North Texas confirmed that DNA from a “John Doe” buried in a pauper’s grave in Macon, Georgia, matches Greer’s, Michigan State Police announced Tuesday.

The investigation was reopened in 2014 using new developments in technology and resources. Results of the DNA testing found that it was 1.9 trillion times more likely that the DNA from the “John Doe” was that of Greer than not, state police said.

“Together, the DNA results and police reports conclude they are one in the same,” state police officials said in a news release announcing the find.

Michigan State Police said “all indications” show that Greer ran away from home and died after being struck by a semi-trailer while hitchhiking along Interstate 75 near Macon, Georgia, some 765 miles south of where he was last seen in Addison, Michigan. His identity had been a mystery to Georgia authorities and Michigan State Police had no details on his whereabouts until the connection was made in December.

A retired Bibb County Sheriff’s Department deputy first connected the dots between the “John Doe” in Georgia and Greer. The retired deputy then notified Michigan State Police, whose investigators later traveled to Georgia to exhume the remains in April.

Arrangements are being made to return Greer’s body to Michigan, state police said. He would have been 55 if alive today, according to his profile on a national database for missing and unidentified persons.

State police eventually collected familial DNA from relatives of Greer’s mother to confirm the match, Michigan State Police Detective 1st Lt. Thomas DeClercq told MLive.com.

“The thing is, you want to feel good about it,” he said. “It is a lot more bitter than sweet. It is sad. A young boy lost his life, you know, running away.”