An Oklahoma City pharmacist who shot and killed a 16-year-old would-be robber was charged Wednesday with first-degree murder.

Jerome Ersland, 57, was being held without bail in the Oklahoma County Jail.

Oklahoma County District Attorney David Prater said in an afternoon news conference that Ersland was justified in shooting Antwun Parker once in the head on May 19. But Prater said Ersland went too far when he shot Parker five more times in the abdomen while Parker lay unconscious on the floor.

Ersland's attorney, Irven Box, said Ersland was protecting himself and two women inside the pharmacy.

"I think he did something in his eyes that protected both himself and two ladies in there," Box said. "He put an end to the threat."

Box said he thinks a jury will exonerate Ersland.

At an afternoon news conference, Prater showed a security video in which two men burst into the pharmacy and one is shot.

Ersland is seen chasing the second man outside before returning, walking past Parker to get a second gun then going back to Parker and opening fire.

The charge alleges Ersland shot Parker while he was incapacitated and lying on his back. Ersland's account of the incident doesn't match the video or the evidence collected at the scene, according to an affidavit written by Oklahoma City Police Detective David Jacobson.

Jacobson said the suspect who ran away from the pharmacy was armed, but no gun was found near Parker.

"Ersland shows no concern for his safety as he walks by Parker, and turns his back to Parker as he walks behind the pharmacy counter," Jacobson said. "Ersland is then seen to put the pistol he is carrying on the counter, and retrieve a second pistol from a drawer."

Ersland used this pistol to shoot Parker on the ground, the detective said.

He said an autopsy determined that Parker had been shot in the head, but was still alive when he was shot in the stomach area and died from those injuries.