CYPRESS, Calif. -- A Lakewood man accused of the St. Patrick's Day killing of a bar patron via pool cue bludgeoning was charged Wednesday with involuntary manslaughter, officials said, according to City News Service.

Richard Lee Thompson, 47, could face up to four years in prison if convicted in the March 17 attack at the Breakers Bar, 4360 Lincoln Ave., on Steven Toole.

Officials said Toole, 45, was unconscious and not breathing after he was hit on the head with the pool cue during a brief confrontation. Thompson was originally arrested on suspicion of attempted murder shortly after the incident, but released from custody when prosecutors decided they needed more time to investigate the case. After two months of investigation that included reviews of an autopsy and crime lab results, Thompson was arrested Tuesday, Cypress police Sgt. Tom Bruce said.

The brief fight between Thompson and Toole apparently involved a beer mistakenly delivered to Toole instead of an acquaintance of Thompson's, according to the Orange County Register.

Thompson apparently told Toole to keep the beer, but during the conversation there may have been some jostling between the two, the newspaper reported, citing a police affidavit. Thompson said Toole shoved him in the chest with both hands, causing Thompson to fall, according to officials. Thompson subsequently jumped up, grabbed a pool cue and used it to hit Toole, according to the paper's description of the police record.

Thompson said he thought he hit Toole in the shoulder area because the blow seemed to land in a soft spot, but an autopsy came back listing the cause of death as blunt-force trauma to the back left side of Toole's head, the newspaper reported.

Thompson left the bar and later called police to determine if the patron had been hurt, officials said.

Thompson later said he believed Toole may have been at the bar because of some discussion between Toole's girlfriend and Thompson's girlfriend, but Toole's girlfriend denied she might have instigated any confrontation.