A former Maryland correctional officer has been charged with felony conspiracy in connection with a beating of an inmate at a medium-security facility.

Eight corrections officers had been charged in the 2008 beating of inmate Kenneth Davis, but none of those cases resulted in a conviction. Some ended in acquittals or hung juries.

Last week, prosecutors with the Civil Rights Division of the Justice Department brought criminal charges against a ninth prison worker.

Ryan Lohr was charged in a Maryland federal court with felony conspiracy to obstruct justice. Lohr was charged by information, an indication that a plea deal is in the works.

Davis, serving a 19-year sentence for robbery, was hospitalized after four beatings in 24 hours at the Roxbury Correctional Institution near Hagerstown, authorities said.

The prison had been placed on lockdown after several inmates assaulted corrections officers while leaving the dining hall.

According to charging papers, Lohr was assigned to the infirmary where Davis was attacked in retaliation for an attack of another corrections officer. Prosecutors said Davis beat up another correctional officer a day earlier in his cell.

Lohr opened the door to Davis' cell and allowed several fellow correctional officers to assault Davis in retaliation for the previous attack. Lohr watched as the other officers kicked and punched Davis about the head, face and body, according to charging papers.

The correctional officers agreed to cover up the assault and say they didn't see or hear anything, documents said.

Lohr directed others to clean up the blood in Davis' cell so it couldn't be used for evidence, court documents said.

A supervisor allegedly erased surveillance tapes by waving what appeared to be a magnet over the tapes and then hid the device in the drop-ceiling.

Davis, 42, was hospitalized for four days with several broken bones. A correctional officer investigating the beating did not recognize Davis when he spoke to him in the hospital.