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Four inmates at Pelican Bay State Prison in Crescent City have been moved into restrictive housing while prison officials investigate another inmate’s death as a homicide.

On Sunday, Michael Challoner, 36, was stabbed multiple times and was transported off prison grounds where he was later pronounced dead.

Guards at Pelican Bay initially found Challoner sparring with another inmate, Joseph Quintero, 36, during “dayroom activities,” the period when incarcerated inmates are allowed to socialize typically in a common space. When they broke up the fight, guards discovered Challoner had suffered multiple “puncture wounds.”

Prison staff provided first aid until an ambulance could arrive to take Challoner to the hospital.

After Challoner was taken away, staff searched a section of the prison, checking inmates and cells for anything that could be linked to the attack.

One inmate, identified as Michael Jones, 49, was searched by prison staff. At the time, he was standing near a cell occupied Oscar Monsibais and Omar Arzate. All three inmates and the cell were searched and guards recovered an “inmate-manufactured” weapon that is believed to have been used during the attack on Challoner.

Quintero, Jones, Monsibais and Arzate have been placed in restricted housing as authorities investigate Challoner’s death, according to the California Department of Corrections and Rehabilitation. Inmate movement within the prison is currently limited.

All five men were serving convictions out of Southern California.

Michael R. Challoner is shown in this mugshot provided by the California Department of Corrections and Rehabilitation on June 13, 2022.

Challoner was received by CDCR in July 2009 out of Ventura County. He was serving a 21-year sentence for voluntary manslaughter, which he committed as a member of a street gang. He received additional prison time for assaulting a fellow inmate with a deadly weapon in 2019 and battering a “non-incarcerated” person in 2016.

The four inmates suspected in having a role in Challoner’s killing were all sentenced in Los Angeles County.

Quintero, most notably, is serving a life-sentence for first-degree murder; Jones had previous convictions for robbery; Monsibais is serving time for assault with a deadly weapon and robbery, as well as multiple parole violations; Arzate is serving a 29-year sentence for assault with a machine gun and kidnapping.

From left: Joseph A. Quintero, Michael Jones, Oscar Monsibais and Omar Arzate are shown in their state prison mugshots provided by the California Department of Corrections and Rehabilitation.
From left: Joseph Quintero, Michael Jones, Oscar Monsibais and Omar Arzate are shown in their state prison mugshots provided by the California Department of Corrections and Rehabilitation.

The prison’s investigative services unit and the Del Norte County District Attorney’s Office are investigating Challoner’s killing and the California Office of the Inspector General was notified on the inmate death.

A motive for the attack is unknown at this time.

Pelican Bay State Prison houses inmates ranging from minimum security all the way to maximum. There are about 1,800 inmates housed at the Far Northern California prison, which employs nearly 1,500 staff.