ROSHARON, Texas (CBSDFW.COM/AP) — A former Texas prison sergeant is slated to stand trial, accused of throwing a handcuffed prisoner onto a concrete floor so viciously that the inmate died.

Lou Joffrion slammed inmate David Witt in August 2017 in an attack that was captured on video at the Darrington Unit in Rosharon, south of Houston.

(Photo by Justin Sullivan/Getty Images)

The Houston Chronicle reports that Joffrion will stand trial in September on an aggravated assault charge.

State officials say Joffrion had just weeks before completed six months of disciplinary probation for another violent encounter with the 41-year-old Witt.

Prison officials Monday condemned Joffrion’s conduct but noted a powerful painkiller in the slain inmate’s blood as a possible cause of the altercation.

Officials didn’t report Witt’s death as a homicide until the full autopsy was completed a year later.

A Texas death row inmate who sued unsuccessfully to try to halt his execution for killing a guard in 1999 tried to convince the U.S. Supreme Court he shouldn’t die.

Robert Pruett was already serving 99 years for a neighbor’s killing when he was convicted in the death of a prison guard who was stabbed in an attack that prosecutors say stemmed from a dispute over a peanut butter sandwich. Pruett wanted to take the sandwich into a recreation yard against prison rules, they said. An autopsy showed corrections officer Daniel Nagle died of a heart attack brought on by the December 1999 stabbing.

No physical evidence tied Pruett to Nagle’s death. At his 2002 trial, prisoners testified that they saw Pruett attack Nagle or heard him talk about wanting to kill the guard. According to some of the testimony, he talked about possessing a weapon as well.

Pruett has said he was framed and that Nagle, an officer for more than three years, could have been killed by other inmates or corrupt officers at the McConnell Unit.

“I never killed nobody in my life,” Pruett testified at his trial. He said he was in a gym when he learned the officer had been stabbed.