Surveillance video shows a mentally ill man shot by a Dallas cop never “lunged” at police before an officer opened fire.

Officer Carden Spencer claimed the man came at him with a knife, forcing him to shoot. But a neighbor’s surveillance video shows that’s not how it happened.

Bobby Bennett, 52, was sitting outside in a rolling chair when two officers arrived. Bennett’s mother had called for help after arguing with her son, who she claims suffers from schizophrenia and bipolar disorder.

The silent video from Oct. 14 shows Bennett suddenly stand up from his chair, but he goes no farther.

He stands still, arms at his side, facing the officers from roughly 20 feet away.

Four or five seconds pass before Officer Carden Spencer opens fire.

Bennett crumples to the pavement, alive but seriously wounded.

Police had said in a news release “the incident escalated which led an officer to fire his weapon” and charged Bennett with aggravated assault.

Police Chief David Brown dropped the charge after viewing the video. He put Spencer on indefinite leave while the shooting is investigated.

Bennett was shot in the stomach. He remains hospitalized at Baylor Hospital.

Neighbor Maurice Bunch watched the shooting from his driveway. His home surveillance camera rolled in the background.

"When the officers told him freeze, he complied," Bunch told WFAA. "He did not move an inch, in suspended animation; he just stood there, you know? Bobby was conscious, he knew exactly what he was doing because I had been talking to him prior."

Spencer’s lawyer told the station the shooting was justified.

"The facts and circumstances known to Officer Spencer at the time completely justify his actions," attorney Robert Rogers said. "Obviously there is much more to this situation than that video."

Bennett’s mother Joyce Jackson said her son grew agitated when she told him not to take one of his drawings outside in the rain. She said police assured her they would send officers trained to deal with people who are mentally ill.

She was still inside when Spencer pulled the trigger.

"It took them no time to start shooting," she told WFAA. "When you’re with a mentally ill person, you don’t just start shooting."

She has hired high-powered Dallas attorney George Milner and plans to sue police.

"In my view, based upon further review of the videotape, this officer crossed the line," Milner told the Dallas Morning News.

The police chief has said his department will do a thorough criminal investigation and refer the findings to the Dallas County District Attorney.