(RICHLAND COUNTY, S.C.) -- A Richland County prison guard is charged with assault after he caused severe internal injuries to an inmate.

According to The State, the inmate was a 52-year-old homeless man who had been arrested multiple times for trespassing in University of South Carolina buildings while looking for shelter. The most recent arrest occurred on February 7 after he was found at the doorstep of the building that houses the University's math and statistics department.

The assault allegedly occurred four days later at the Alvin S. Glenn Detention Center where Robin E. Smith, 38, was a guard. A spokesman for the Richland County Sheriff's Department told The State that the beating was "prolonged," and that it included boot strikes to the head, neck and chest.

The victim suffered a collapsed lung, two broken ribs, a fractured vertebrae and internal injuries, but was not taken to a hospital until four days later. Police say he might die from his injuries.

Smith was released February 25 on a $20,000 recognizance bond after being charged with assault and battery of a high and aggravated nature. He was fired from the prison on the same day he was released.

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