Walker died the next day at a hospital in Springfield.
In an interview at the police station, Smith changed his story from what he said at the scene. He claimed he was sitting right next to Walker on a mattress in the living room, showing her how to use the .38-caliber revolver. Smith said he shook bullets out of the revolver's cylinder and believed all the rounds had fallen on the floor.
Smith told detectives that he "placed the cylinder back in the gun and pushed the rod/pin used to retain the cylinder back into place. He said when he pushed the rod into place, the gun discharged. Smith indicated he was holding the gun in his hands and the barrel was facing to his left. Smith reported he discovered Walker had been injured and carried her to the neighbor's house," the probable cause statement says.
Walker was shot in the head. Emergency room personnel and the medical examiner said the bullet entered the left side of her forehead and traveled downward toward the right ear, but did not exit.
Investigators don't think Walker could have been shot while Smith was sitting right next to her as he described to detectives.
"When you would handle the weapon down at this level, that would be different than an injury that would enter someone's head from above at a different angle," Patterson said.
Smith, a convicted felon, faces three charges, including second-degree murder, armed criminal action, and being a felon in possession of a firearm. Prosecutors asked for a $500,000 bond.
Smith has been in a state prison since shortly after the shooting. Prosecutors identified him as a suspect and pushed for his probation to be revoked from an earlier conviction. Smith has convictions in 2005 and 2008 for stealing.
If Smith is convicted, he faces a prison sentence of 10 to 30 years for second-degree murder, at least three years for armed criminal action, and up to four years for being a felon in possession of a firearm.