Marcus Bates just happened to be outside the Elmwood Elks Lodge in Norristown as Garfield Williams Sr. tussled in the doorway with a trio of men in 2010.

Williams was using a gun to club one of the men when it accidentally discharged. The bullet flew through the open door and struck and killed Bates as he was getting into his car.

Williams, 40, of Allentown, initially was charged with first-degree and third-degree murder. Last week, just as his trial was to begin, he pleaded guilty in a plea agreement to involuntary manslaughter and a weapons charge for being a felon barred from having a gun.

The Montgomery County District Attorney's Office and Williams' attorney differ on some aspects of the incident, including the cause of the fight.

Williams' attorney, Guy R. Sciolla of Philadelphia, said the three men had been bothering Williams' wife and two of his sisters-in-law as they sat inside the Elks Lodge on Green Street. One of the women pulled out the gun from her purse in self-defense, and Williams grabbed it out of her hand to avoid a shooting, Sciolla said.

There were too many differing accounts to conclusively determine what happened in the bar before the shooting, Assistant District Attorney Nathan J. Schadler said.

But the sides did agree that the death was accidental and did not warrant the more severe charges.

"We did not feel that we met the burden of malice under the definition of murder," Schadler said. "We did not have any premeditation."

Sciolla said he and Williams had said all along that the shooting was accidental: "There was no intent to kill anybody."

Still, Schadler said, someone did die, which was why the charges Williams pleaded guilty to were serious.

"The tragedy was that an innocent person lost their life," he said.

Williams' sentencing is scheduled for April 2 in Montgomery County Court.

Contact Carolyn Davis at 610-313-8109, cdavis@phillynews.com, or @carolyntweets on Twitter.