A child killer was beaten and strangled to death by his cellmate at the Oklahoma State Penitentiary in McAlester. This is a representational image of a guard at the Lee Correctional Institution in Bishopville, South Carolina, April 16, 2018. LOGAN CYRUS/AFP/Getty Images

A prisoner beat and strangled a convicted child killer to death in their shared cell, officials at the Oklahoma State Penitentiary in McAlester said.

Raymond Pillado murdered his cellmate, 59-year-old Anthony Palma, on Jan. 11. Local news website KFOR-TV reported they received a copy of the medical examiner’s report Wednesday that described the cause of death as “ligature strangulation and blunt force trauma to the head.” It was later determined that Palma was strangulated by an electrical cord.

Though Palma’s death was reported in January, the cause of death was under investigation and the officials at the Department of Corrections believed he was killed due to the nature of his crime. A spokesman for the DOC, Matt Elliott, said, “Those who are serving time for victimizing children, they are definitely more vulnerable.”

Palma was sentenced to life in prison in 2017 for a cold case murder of an 8-year-old girl whose body was never found. Kirsten Hatfield was kidnapped from her house in Oklahoma suburb of Midwest City and until 2015, the case remained cold. The DNA from blood on the girl’s bedroom window and her underwear, found in their yard, linked to Palma. He was found guilty of kidnapping, sexually assaulting and killing the girl before he dumped her body at an unknown location. Palma lived near Hatfield’s family.

Even after Palma’s arrest and conviction, Hatfield’s body was never located. Authorities were hopeful they would find the body after an interview with Palma later this year. “We’ve not had closure on this case and we may never have closure because we wanted to find her body and bring her home. Our hopes are, with any case like this, the suspect who’s convicted…in this case, it was Anthony Palma… that hopefully he would have some inkling of a conscience, maybe intervention by a higher power, maybe God, and come out and tell us exactly what he did with her.”

Palma’s killer, 35-year-old Pillado, was serving several life sentences for murder and shooting with intent to kill among other charges. A corrections officer found Palma on the floor of his cell covered in a blanket. When he lifted the blanket, the officer saw “blood all over the floor and inmate Palma appeared to not be breathing.”

In a similar case, on Tuesday an inmate from the Mohave County jail in Phoenix was given a 21-year jail sentence and even years of supervised probation for killing his cellmate in 2017. Gaven Robel, 26, pleaded guilty to second-degree murder along with a few other charges. He was arrested in October 2017 for using fake prescriptions to obtain thousands of oxycodone pills fraudulently. According to other inmates, Robel repeatedly stomped on Ryan Couch’s neck and head. He died two weeks later.