A 73-year-old Oklahoma reserve deputy who accidentally shot and killed a man during an undercover gun sting on April 2 was charged today with second-degree manslaughter, according to a press release from the Tulsa County District Attorney's Office.

“[The reserve deputy] is charged with Second-Degree Manslaughter involving culpable negligence. Oklahoma law defines culpable negligence as ‘the omission to do something which a reasonably careful person would do, or the lack of the usual ordinary care and caution in the performance of an act usually and ordinarily exercised by a person under similar circumstances and conditions,’” District Attorney Steve Kunzweiler said in the statement.

Earlier Monday, Tulsa County Sheriff Stanley Glanz described the reserve deputy as a longtime friend who made "an error" last week when he fatally shot an unarmed man trying to flee deputies during an undercover operation to retrieve stolen guns.

Glanz also told the Tulsa World he had no plans to change the deputy reserve program but that it will be looked as part of the Sheriff's Department routine review of operations.

According to the Sheriff's Office, the reserve deputy had intended to use a Taser on Eric Courtney Harris as Harris was being subdued during an undercover gun buy on April 2 but instead pulled his gun and fired one shot, killing Harris.

Glanz responded to critics who have said the reserve deputy was too old to be a reserve deputy. The Sheriff's Office once had an 81-year-old deputy, Glanz said.

"I am 72 years old, and I think I am still active," the sheriff said.