Tracy Gilpin was only 15 when she went out on Oct. 1, 1986, to attend a party.
The Kingston, Massachusetts, teenager — who was initially believed to be missing — was never seen alive again.
Three weeks later, her body was discovered in Myles Standish Park in Plymouth. Authorities determined that she had been savagely killed because she had a massive skull fracture.
Since then, Tracy's killer has remained free.
But on Friday night, 31 years later, Massachusetts State Police said "information was developed" that led them to team up with authorities in Troutman, North Carolina, to bring a 61-year-old man into custody. Michael Hand was placed under arrest and charged him with being a fugitive from justice and pinning him "for the 1986 homicide" of Tracy.
Investigators say they never gave up hope to bring Tracy's killer to justice — especially Tracy's sister, Kerry Gilpin, who is now the Massachusetts Police colonel.
"For the past three decades, we have remained hopeful that Tracy's murderer would be identified," Gilpin said in a statement. "The much-welcomed news of an arrest in the case leaves us cautiously optimistic that justice for Tracy is within reach."
She went on to talk about how she is not just thinking of getting justice for her family but "all the families who have lost loved ones to violence."
"We will continue to work tirelessly to find justice for all murder victims," she added.
Hand is being held in the Iredell County Detention Center in North Carolina. He is set to face an extradition hearing on Monday.
If Hand doesn't fight extradition to Massachusetts, he will be arraigned on murder charges at the Plymouth District Court, authorities at the Iredell County Detention Center said.