OKLAHOMA CITY --- Confronted by two holdup men, pharmacist Jerome Ersland pulled a gun, shot one of them in the head and chased the other away. Then, in a scene recorded by the drugstore's security camera, he went behind the counter, got another gun, and pumped five more bullets into the wounded teenager as he lay on the floor.

Now Mr. Ersland has been charged with first-degree murder in a case that has stirred a furious debate over self-defense and turned the pharmacist into something of a folk hero.

Mr. Ersland, 57, is free on $100,000 bail, courtesy of an anonymous donor. He has won praise from the pharmacy's owner and received cards, letters and checks from supporters.

"His adrenaline was going. You're just thinking of survival," said John Paul Hernandez, 60, a retired Defense Department employee who grew up in the neighborhood.

District Attorney David Prater said Mr. Ersland was justified in shooting 16-year-old Antwun Parker once in the head, but not in firing the additional shots into his belly. The prosecutor said the teenager was unconscious, unarmed, lying on his back and posing no threat when Mr. Ersland fired what the medical examiner said were the fatal shots.

Anthony Douglas, the president of the Oklahoma chapter of the National Association for the Advancement of Colored People, called it an "execution-style murder" and praised the district attorney for bringing charges. Mr. Ersland is white; the two suspects were black.

If convicted, Mr. Ersland could be sentenced to life in prison with or without parole, or receive the death penalty.

The 14-year-old boy accused of wielding the gun in the robbery was arrested Thursday. The district attorney said he will seek murder charges against the teenager, a man accused of being the getaway driver and another man suspected of helping talk the teens into the crime.