GRAYSON, Ky. (AP) — A West Virginia sex offender has pleaded guilty to killing a mother and two young girls at their eastern Kentucky home, then setting the place on fire.

The Ashland Daily Independent reported that Robert Drown of Kenova, W.Va., pleaded guilty Tuesday to murder and other charges in the deaths of 31-year-old Jennifer Ison and her two daughters, 10-year-old Shannah, and 3-year-old Marissa.

The plea removes the possibility of a death sentence for Drown. He is scheduled to be sentenced to life in prison without parole at a hearing in Carter County on May 4.

Ison and her daughters were killed in May 2007. Their bodies were found in a burned-out mobile home in the Hitchins community, about 25 miles from the Kentucky-West Virginia border.

The victims’ bodies were found May 9, 2007, inside their mobile home, which had been set on fire, police said.

Jennifer Ison was strangled, Shannah died from blunt force trauma to the head and Marissa died in the fire, police have said. One of the girls was raped, police said.

The mother was a registered nurse in the labor and delivery department at Cabell Huntington Hospital in West Virginia.

Drown was arrested in West Virginia and was originally held there for failing to register as a sex offender.

Drown had served about 4 1/2 years in prison on charges of sexually abusing an adult female, according to the West Virginia sex offender registry.