SCOTTSDALE, Ariz. -- Police were excavating the back yard of a Scottsdale home Tuesday in a search for the remains of a teenage boy killed almost 30 years ago.

Greg Holman, then a 14-year-old freshman at Saguaro High School, was reported missing Oct. 8, 1978, according to the East Valley Tribune.

Police initially considered Holman a runaway, but a tip from his sister in November 1992 led detectives to the former back yard of Holman's friend, Jon Benson, where they found some of Holman's remains.

Benson was also 14 when Holman disappeared. After finding Holman's remains in the yard, police named Benson as a suspect in the case but were unable to develop enough evidence to charge him.

Benson, now 45, is in prison for luring a child for sexual exploitation. Phoenix police arrested him two years ago and he was imprisoned last fall.

Scottsdale police Sgt. Mark Clark on Tuesday said new information led cold-case detectives to believe there are more of Holman's remains buried in Benson's former back yard. Police and an archaeologist spent the morning digging under a tennis court put in place by subsequent owners of the house.