TULSA, Okla. (AP) — A white reserve sheriff's deputy thought he was holding a stun gun, not his handgun, when he fatally shot a black suspect during an arrest that was caught on video in Tulsa, Oklahoma, police said.

The video of the April 2 incident shows a Tulsa County deputy chase and tackle Eric Harris, 44, whom they accuse of trying to sell an illegal gun to an undercover officer.

A deputy is heard telling Harris, "I need you to roll on your stomach." At about the same time, a woman is heard in the background saying, "Stop fighting."

While the deputy is subduing Harris on the ground, a gunshot rings out and a man says, "Oh, I shot him. I'm sorry."

Authorities identified the shooter as 73-year-old reserve deputy Robert Bates and said he meant to use his stun gun.

Harris screams, "He shot me. Oh, my God," and a deputy replies: "You f---ing ran. Shut the f--- up."

When Harris says he's losing his breath, a deputy replies, "F--- your breath."

Harris was treated by medics at the scene and died in a Tulsa hospital.

The video was released over the weekend at the request of Harris' family. It was recorded by deputies with sunglass cameras, Tulsa County Sheriff's Office officials said. They said Bates believed he was holding a Taser and intended to incapacitate Harris when the fatal shot was fired.

Reserve deputies are generally volunteers, often with other full-time jobs. Bates is an insurance company executive assigned to the Violent Crimes Task Force.

The sheriff's office told the Tulsa World that it has more than 100 reserve deputies, who "have full powers and authority" of a deputy while on duty, and that it's not unusual for them to be on an assignment with units such as the Violent Crimes Task Force.

Tulsa Police Sgt. Jim Clark, who investigated the shooting at the request of the sheriff's office, concluded that Bates had been under the influence of a phenomenon known as "slips and capture," which occurs when a person's behavior "slips" off the intended course of action because it's "captured" by a stronger response.

An attorney for Harris' family, Dan Smolen, did not return a telephone call Sunday seeking comment. The family has not commented publicly since the video's release.

Results of the investigation have been turned over to prosecutors, who will decide whether to file criminal charges.

Reserve deputies are generally volunteers, often with other full-time jobs. Bates is an insurance company executive assigned to the Violent Crimes Task Force.

The sheriff's office told the Tulsa World that it has more than 100 reserve deputies, who "have full powers and authority" of a deputy while on duty, and that it's not unusual for them to be on an assignment with units such as the Violent Crimes Task Force.