Just minutes after he shot and killed his mother, Christopher Shumey was worried that his neighbors might see him sitting in the back of a police car.

“I wanna get out of here,” Shumey told a San Luis Obispo police officer as he gazed outside the squad car, later adding, “All these people, looking around and stuff.”

During Shumey’s murder trial Tuesday, jurors saw a video recorded in the squad car on Sept. 17, 2011, after Shumey shot and killed Karen Shumey, 65, with a 12-gauge shotgun.

While Shumey, 36, nodded off in court several times Monday, he appeared more alert Tuesday. At times, though, he could be seen whispering to someone who wasn’t there, occasionally making gestures with his hands.

Shumey’s attorney, Pierre Blahnik, said his client was mentally ill and not in control of his actions when he shot his mother twice. But Deputy District Attorney Karen Gray said Shumey knew what he was doing. The video from the police car, she said during her opening statement, is part of that proof.

The video showed Shu-mey anxious to leave but not disheveled. When he spoke to Officer Eric Lincoln, he was articulate and calm.

“What’s the procedure at this point?” Shumey asked Lincoln. When Lincoln said a detective was on the way, Shumey seemed to grow more impatient.

Later, he gave Lincoln his name, address and name spelling.

“I just want to get out of here,” he repeated, adding, “I should have shot myself.”

Blahnik said Shumey — who had previously been diagnosed with schizoaffective disorder — had intended to kill himself that day, but his suicide attempt was interrupted when his mother came to the door. For unknown reasons, Blahnik said, Shumey then turned the gun on his mother, an eighth-grade teacher from Arroyo Grande.

Shumey didn’t watch or show any emotion as Gray displayed photos of his mother’s lifeless body and a large piece of her skull, which landed one floor below the apartment.

Both of Shumey’s parents had tried to get him help for his mental illness. But Shumey, who holds a degree in film and digital media from UC Santa Cruz, had stopped taking his medication, Gray said.

He allegedly stole a rifle and a shotgun from his father’s storage unit, then purchased ammunition.

The day of the shooting, Shumey and his mother had argued, prompting Karen Shumey to leave her son’s apartment so he could cool off. When she returned, he fired two shots toward his balcony, one hitting her in the back, another in the head.

As police responded to the shooting, Shumey fired one shot in their direction — resulting in a charge of assault with a deadly weapon on a peace officer — and asked police to shoot him.

“I’ve just shot my mom,” he allegedly said. “I can’t kill myself. I don’t have the guts. I want you to shoot me.”

When police asked why he shot his mother, Shumey allegedly said, “I don’t know.”

Police later persuaded him to surrender.

Shumey has pleaded not guilty by reason of insanity.