Attorneys for the pharmacy and distributor declined to comment about the request to intervene in the lawsuit.
Prater said the legal action is the first in a planned crackdown on prescription drug abuse.
“It's causing a large number of overdose deaths on our streets,” Prater said. “You're going to see — more and more — our office, partnering with the bureau of narcotics and DEA, to determine what doctors and what pharmacies in our jurisdiction are turning their heads at the diversion of these prescription drugs to nonmedical street use.”
The DEA is the U.S. Drug Enforcement Administration.
The fatal shooting of the robber in May 2009 touched off a national debate over the pharmacist's actions. One video of the robbery made from security camera recordings has been watched more than 1.1 million times on YouTube. Thousands signed petitions last year after the jury trial. The petitions called the verdict an outrage.
Prosecutors said Ersland was justified when he first shot the unarmed robber, Antwun “Speedy” Parker, 16, in the head. They said he was wrong when he got a second gun after chasing an accomplice away and shot Parker five more times.
Prosecutors at the trial called the final shots an execution. They said Parker was unconscious and unmoving on the floor.
Ersland said he was defending himself and two female co-workers. He claimed the masked robber was getting back up.
A second robber, Jevontai Ingram, had fled already. Ingram, then 14, did have a gun.
Two men who planned the robbery were convicted of first-degree murder at a separate trial. They had ordered the teenagers to ask for the prescription drug OxyContin, according to testimony at their trial.
Prater said he now believes the two men, who hung around the northeast side of Oklahoma City, chose Reliable Discount Pharmacy miles away because of the store's reputation. “That had to be the word on the street because there was no other reason they would have targeted that pharmacy,” the district attorney said.