Updated

An Arizona inmate was killed behind bars — beaten to death by the man who shared his cell. Authorities say the motive behind the attack was that he was about to be released and deported back to Mexico.

When detectives first arrived at the Florence Correctional Center, they found 55-year-old Michael Patrick McNaughton dead and his cell mate, 43-year-old Roberto Venegas-Fernandez nearby.

Initially, they thought the two were involved in a fight.

"It wasn't what appeared to be a fight at all, but a very deliberate intentional murder," said Pinal County Sheriff Paul Babeu.

Both inmates were being housed at the private prison for sex crimes. They arrived on Friday, November 15th and by Saturday morning, Fernandez had strangled the victim to death.

"This was planned out in an effort to ensure that he would not leave the United States," said Babeu.

According to the sheriff, Fernandez is an undocumented immigrant and was approaching his release date.

"He told our detectives he liked three meals a day. The jail guards were very nice to him and he was afraid that upon his release he would be deported back to Mexico. He wanted to be sure that he wouldn't be deported back to Mexico," said Babeu.

And to be sure he would get the most serious charge, he also bit the victim's private area.

"He choose to freely speak to homicide investigators and readily admitted this, why he did it," said Babeu.

Both inmates were prisoners of the U.S. Marshal's Service. They were from the San Diego area.

The Florence Facility is operated by the Correctional Corporation of America, the largest private prison company in the U.S.  We reached out the private prison company Tuesday afternoon and never heard back.

The Pinal County Sheriff's Office is recommending that prosecutors charge Venegas-Fernandez with first-degree murder.

For more Arizona news, check out www.myfoxphoenix.com

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