A California inmate now stands accused of torturing and beheading his cellmate, according to reports.

Convicted murderer Jaime Osuna has been accused of the brutal torture and death of his cellmate at Corcoran State Prison in the Fresno suburb of Corcoran, California. The man was killed in the early morning of March 9 and died of blood loss from “multiple sharp force trauma injuries,” charging documents state.

The 31-year-old convict is accused of using a sharp metal object wrapped in string to act as a handle to murder his cellmate, 44-year-old Luis Romero, KCRA reported.

The attack occurred overnight, and prosecutors are not sure how much of the dismemberment occurred while the victim was still alive. Prosecutors added, “We do believe that the victim was conscious during at least a portion of the time.”

“This is the most gruesome case that I have seen in terms of heinousness in the slaying,” Phil Esbenshade, assistant district attorney of Kings County, said in a statement.

Esbenshade added that it is not known if anyone heard the attack during the nighttime.

Osuna already pleaded not guilty during his first court appearance on Thursday. But the suspect could face the death penalty for an act that “was especially heinous, atrocious, or cruel, manifesting exceptional depravity.”

Along with a charge of murder, Osuna was charged with torture, mayhem, and weapons possession. The torture charge said that Osuna acted “with the intent to cause cruel and extreme pain and suffering for the purpose of revenge, extortion, persuasion and for a sadistic purpose.”

Osuna was already serving a life sentence (with the possibility of parole) for the murder of Yvette Pena, who was found dead in a Bakersfield motel in 2011.

The suspect has been transferred to a prison in Stockton that specializes in prisoners who need mental health treatment.

Follow Warner Todd Huston on Twitter @warnerthuston.