WAXAHACHIE, Texas — An Ellis County detention officer in Texas was killed Monday in an attack by an inmate that Ellis County Sheriff Brad Norman described as a “heinous, horrific, purposeful murder.”

Sheriff Norman said during a Tuesday press conference that Arron Semeion Thompson, 45, was being returned to his cell following the one hour he was allowed out of his lockup each day when the brutal attack occurred.

The sheriff identified the deceased detention officer as 28-year-old Isaiah Patrick Bias. Thompson has subsequently been charged with capital murder, NBC 5 DFW reported.

Officer Bias, who worked at the Ellis County Sheriff’s Office for more than six years, was fatally beaten Monday afternoon at the the Wayne McCollum Detention Center in Waxahachie, south of Dallas.

“Most of the time, law enforcement officers and detention officers deal with good folks having a bad day. Occasionally, we deal with bad folks,” said Sheriff Norman. “I can honestly say that my staff, over the last day, has dealt with pure evil. May God bless Isaiah’s family, friends and colleagues.”

Sheriff Norman said Officer Bias was a family-oriented person and held in high esteem by his colleagues, reported the New York Post.

“He was one of the kind of guys who if you needed help, he’d come help you,” Sheriff Norman declared.

Thompson has been in custody since last month on charges resulting in assault of a public servant, public intoxication and evading arrest. His bond in the death of Officer Bias was set at $2 million.

Arron Semeion Thompson

The Texas Rangers are handling the homicide investigation.

Sheriff Norman said he supported the death penalty in Thompson’s case but noted that it was up to the Ellis County District Attorney’s Office to decide if they would seek it. A person convicted of capital murder in Texas face a punishment of either life in prison without parole or death.