Convicted killer from Twin Falls investigated after cellmate's beating death

A man serving time on a drunken driving charge was beaten to death in an Idaho prison, and officials say his cellmate — who was convicted of killing his three small children more than a decade ago — is a suspect in the case.

Idaho Department of Correction spokesman Jeff Ray wrote in a prepared statement that staffers at the prison south of Boise learned Friday that Glenn Arthur Cox had been assaulted.

They found the 52-year-old Cox unresponsive in the cell he shared with 45-year-old James Junior Nice.

Medical staffers attempted to resuscitate Cox, but he was pronounced dead a little less than an hour later.

The Ada County Sheriff's Office is investigating the case, and spokesman Patrick Orr says Nice has been moved to the state's maximum security prison in the meantime.

Ray declined to answer questions about the two men, including how long they had been sharing a cell. He said the department didn't want to say or do anything that could potentially interfere with the Ada County sheriff's investigation.

Orr said Cox and Nice were the only two people in the cell when the assault occurred.

Nice is serving three life sentences for killing his twin 6-year-old boys and his 2-year-old daughter with rat poison and medications at their Twin Falls home.

Cox was serving an eight-year prison term for a felony driving under the influence conviction handed down in Bonneville County in 2015. When he was sentenced, the judge said he would be able to apply for parole after serving one year of the term.

Nice was sentenced to three consecutive life terms in Twin Falls County in 2006. He agreed to plead guilty to murdering his three kids in exchange for avoiding a possible death sentence.

His children, twins Justin and Spencer, and Raquel, were found dead Dec. 21, 2005, in a house in Twin Falls. At the time, police said Nice told them he didn't want the kids to suffer through the divorce.

Authorities said Nice also tried to poison himself but survived.

Another child in the family died a year earlier, prompting state officials to temporarily remove the kids from their parents' custody. Twenty-two-month-old Ian Nice was found drowned in a park in May 2004.

At the request of the Idaho Department of Correction, the Ada County Sheriff’s Office is investigating the death of an inmate following an assault at the Idaho State Correctional Institution.

Correctional staff was notified at 12:56 a.m. that Glenn Arthur Cox, IDOC No. 40455, had been assaulted.

When correctional officers entered Cox’s cell, they found him unresponsive on the floor. Medical staff initiated CPR and paramedics were called. Cox was pronounced dead at 1:45 a.m.

Correctional staff secured Cox’s cell as a crime scene and notified the Ada County Sheriff’s Office.

Cox’s cellmate, James Junior Nice, IDOC No. 83854, was transported to Idaho Maximum Security Institution pending the investigation.

ISCI is a 1,446-bed, medium-security, men’s prison south of Boise.