VINITA, Okla. (AP) — A Kansas man charged in the 1999 deaths of an Oklahoma couple and the disappearance and presumed deaths of their teenage daughter and her friend has pleaded guilty to an accessory to murder charge.

Ronnie Busick, 68, entered a guilty plea on Wednesday in an agreement with prosecutors. He was sentenced to 15 years, serving 10 years in Oklahoma Department of Corrections custody and five years under supervised release. Busick may get a lesser sentence is he provides information that leads to the recovery of the two Craig County teens, according to Tulsa World.

Busick is the only suspect still alive. He is currently being held in the Craig County jail in Vinita, about 60 miles northeast of Tulsa. As part of the deal with prosecutors, charges of arson and kidnapping were dropped in the deaths of Danny and Kathy Freeman; their 16-year-old daughter, Ashley; and her best friend, Lauria Bible.

The two girls have not been found despite numerous searches.