The Oklahoma Department of Corrections is continuing to investigate the inmate death of Anthony Palma.

One step in the investigation is figuring out how a prison killing happened in a maximum security facility.

“This is one of those things that sometimes can happen even if you're employing proper correctional practices. All of our security checks,” DOC Spokesperson Matt Elliott said.

A guard found convicted murderer Anthony Palma unresponsive in his cell Friday, and lifesaving efforts failed to revive him.

The suspect is Palma's cellmate, a man serving multiple life sentences for a murder conviction of his own.

“We're pretty certain how it happened, and we have some charges being filed at this point,” Elliott said.

Palma was in prison for killing a child in Oklahoma County, but Elliott says despite his character, his killing is still a crime.

The DA will file something if they see enough evidence to warrant a charge, and then once their court date approaches, then that inmate who's charged gets transferred over to a county jail,” Elliott said.

As officials investigate, Palma's family says this is a tragic situation for all involved.

“We've got questions we'll never have answers to. We're sad, angry. Why couldn't they protect him?” Palma’s former mother-in-law Leona Stansberry said.

The medical examiner will conduct an autopsy to decide Palma’s manner of death.