SHIRLEY, Mass. (AP) — An inmate serving a life sentence for murder has been charged with using a heavy piece of weightlifting equipment to violently attack a Massachusetts prison guard who remains in the hospital more than a month later.

Roy Booth, 40, has been charged with armed assault with intent to murder and other offenses in connection with the Aug. 31 attack on Corrections Officer Matthew Tidman, Middlesex District Attorney Marian Ryan said in a statement Wednesday.

He will be arraigned at a later date. It could not immediately be determined whether he has an attorney.

Tidman, 36, an officer at Massachusetts Correctional Institution-Shirley, was monitoring the recreation area at the medium security facility when he was struck multiple times with a 10- to 15-pound (4.5- to 6.8-kilogram) metal pole the suspect had unscrewed from the weightlifting apparatus, according to the preliminary investigation, Ryan’s office said.

Tidman was struck in the head and face, according to the Massachusetts Correction Officers Federated Union.

Other guards restrained Booth and provided aid to Tidman, who was flown to Lahey Hospital & Medical Center in Burlington where he remains in intensive care, according to Ryan’s office.

“Every day he is fighting for his life but he progresses slightly every day,” said Kevin Flanagan, a member of the union’s executive board.

Authorities did not disclose a motive, but Flanagan said the attack was apparently unprovoked.

Booth is serving a life sentence in connection with a murder in Virginia, but had been transferred to Massachusetts in March 2021 under the Interstate Corrections Compact, Ryan’s office said.