HILLSBORO, Ore. (KOIN 6) — A St. Helens man was sentenced on Monday for the death of a teenage girl whose body was found in a ditch in October 1982.

Earlier this month, a jury convicted Kenneth Lee Hicks, 52, for the aggravated murder of 17-year-old Lori Gale Billingsley.

Washington County Senior Deputy District Attorney Bracken McKee, July 13, 2015 (KOIN)

Hicks was sentenced by Washington County Circuit Court Judge Thomas W. Kohl to life in prison. He will have to serve a minimum of 20 years. He will be able to ask for parole after serving 15 years.

Hicks was 19-years-old when he killed Billingsley on Oct. 9, 1982.

Senior Deputy District Attorney Bracken McKee said Hicks has a complete inability to feel any form of emotion for anyone but himself.

Lori Billingsley in a photo used in a Cold Case flyer from the Washington County Sheriff's Office, undated

Investigators say that Billingsley was raped, strangled and physically assaulted. Hicks tossed the girl’s body in a ditch, according to detectives. The case puzzled law enforcement for years.

In 2010, retired Washington County Sheriff’s Deputy Michael O’Connell, started reviewing the cold case. He recalled being a newbie on the force when Billingsley was murdered and said the case stuck with him.

Detectives sent evidence back to the Oregon State Police Crime Lab. A warrant for Hick’s DNA was obtained. The crime lab determined that sperm taken from Billingsley body was a 1-in-10-billion match, according to prosecutors.

Retired Washington County Sheriff’s Deputy Michael O’Connell, July 13, 2015 (KOIN)

O’Connell praised the work of the lead detectives back in 1982.

Hicks did not make any statements before he was sentenced. McKee said it was a telling sign of Hick’s lack of remorse.

“Until he accepts responsibility, and starts the healing process, there is no change,” McKee said in court. “And I don’t expect there ever will be.”