Marc Karun, 53, was arrested by Maine State Police on a fugitive from justice warrant out of Norwalk, Connecticut. He is being held at the Penobscot County Jail and will have a bail hearing Friday at the Penobscot Judicial Center.
The warrant said Karun sexually assaulted and killed the girl while she was on school grounds.
Lt. Terry Blake of the Norwalk Police Department said the girl who died was Kathleen Flynn, who was last seen on Sept. 23, 1986 leaving her middle school on a walking path that led to her nearby home.
According to Facebook posts about the unsolved homicide, she was strangled to death.
Karun is on the Maine Sex Offender Registry for a 1989 conviction in Connecticut that sent him to prison for six years.