LARNED, Kan. (AP) — An inmate who raped and killed two young sisters in Topeka nearly 30 years ago has died.

The Kansas Department of Corrections said Monday it was investigating the death of 66-year-old Nolan D. Prewett. The Topeka Capital-Journal  reports that he died Sunday night at the Larned Correctional Mental Health Facility.

Corrections department spokesman Adam Pfannenstiel says no additional information is available.

Prewett was serving time for the 1986 deaths of the 3- and 6-year-old sisters. Their nude bodies were found in his basement, wedged between a furnace and a wall.

Beforehand, Prewett had been in and out of Veterans Affairs medical centers. The slain girls’ mother alleged the VA was negligent and received an undisclosed settlement.

Prewett would have become parole eligible for the first time in November 2017.