BOSTON — The commander of the Massachusetts State Police is thanking law enforcement for making an arrest in the 1986 killing of her teenage sister.

Authorities say 61-year old Michael Arthur Hand of Troutman, North Carolina, was arrested Friday and faces a murder charge in the death of 15-year-old high school freshman Tracy Gilpin.

The victim is the sister of current state police Col. Kerry Gilpin.

Col. Gilpin said the arrest “leaves us cautiously optimistic that justice for Tracy is within reach.”

Tracy Gilpin, of Kingston, Massachusetts, disappeared on Oct. 1, 1986. Her body was found in Myles Standish State Forest in Plymouth three weeks later.

District Attorney Timothy Cruz says Tracy Gilpin from “a massive blow to the head.”

It was not immediately clear if Hand has a lawyer.