Accused Post Office Killer Injured : Suspect: Officials say Mark Hilbun was acting bizarrely when he fell from jail walkway. There is no indication of a suicide attempt.

Mark Richard Hilbun, the former Dana Point postal worker accused of murdering his mother and a former co-worker, suffered a possible broken vertebra and a slight concussion Monday in a fall from a second-story walkway in Orange County Jail, authorities said.

Hilbun, 39, who is being held in protective custody without bail, was injured about 7:15 a.m. The incident occurred shortly after he was allowed out of his cell for his required time in one of the jail’s day rooms, where some inmates eat their meals and can “relax and watch television,” said Lt. Dick Olson of the Orange County Sheriff’s Department.

“He started to exhibit bizarre behavior and verbally threatened another inmate still in his cell. Hilbun also started beating on the glass door of the inmate’s cell with his hands,” Olson said.

As guards summoned a supervisor and medical staff, Olson said, Hilbun lay down “on his stomach on the second floor walkway and pushed his upper body out over the day room.” After clinging momentarily to the railing, Hilbun “let go, falling to the day room floor. He landed on his head, neck and upper shoulder,” Olson said.

Hilbun was alone on the walkway at the time of his fall but was being observed by guards in a nearby control tower, Olson said.

“Once he slid himself out there, down he went . . . to the next floor, about eight feet,” Olson said.

Olson added that Hilbun refused medical treatment immediately after the fall but was later taken under armed guard to a hospital for treatment.

Hilbun’s attorney, Deputy Public Defender David Biggs, said jail officials refused to give him details of the fall.

“We’ve called and the jail (spokesperson) said, ‘We’re not giving out any information,’ ” Biggs said.

Olson said there was no indication that Hilbun was attempting suicide, but he added that the Sheriff’s Department would review the incident and make a determination “of what his intentions were.”

Hilbun is awaiting a preliminary hearing next month on a variety of felony charges stemming from a two-day rampage that began in the before dawn May 6. Police believe that Hilbun stabbed his mother to death in her Corona del Mar apartment, then drove to a Dana Point post office where he they say he shot a fellow postal carrier to death and wounded another.

As police carried out a massive manhunt, Hilbun allegedly shot and wounded at least four more people in three attacks in Dana Point, Newport Beach and Fountain Valley. He was arrested shortly after midnight May 8 while watching television in a Huntington Beach sports bar.

Times staff writer Lily Dizon contributed to this story.