Nebraska authorities say an inmate on death row for the 1985 cult killings of two people, including a 5-year-old boy, had died in custody.

Spokeswoman Jessica Houseman for the Tecumseh State Correctional Institution in southeast Nebraska confirmed Monday that 66-year-old Michael Ryan died in prison. Houseman said he died around 5:45 p.m. Sunday. She said an autopsy would be performed to determine the cause of death.

Ryan was convicted in the torture and killing of 26-year-old James Thimm at a southeast Nebraska farm near Rulo, where Ryan led a cult, and in the beating death Luke Stice, the 5-year-old son of a cult member.

Ryan has been on death row since his convictions.