Tulsa County Sheriff Stanley Glanz apologised on 20 April to the family of Eric Harris, who was shot and killed earlier in April by a reserve deputy who mistook his gun for a taser.
"We are sorry Eric was taken from you, for this I am sorry that we all we involved and my sympathy goes out to that family. I think it is very important any time a life is lost in out community, that we all need to stop and hesitate and say a prayer," Glanz told reporters.
An Oklahoma reserve deputy, who fatally shot a man when he said he accidentally grabbed his gun instead of his taser said his mistake could have happened to anyone.
Volunteer deputy Robert Bates has denied reports that he was not properly trained amid allegations his permit paperwork has been misplaced and falsified.
Reporters asked Glanz about allegations of Bates' training records being falsified. Glanz responded "No sir, not that I'm aware of."
Oklahoma prosecutors charged Bates, 73, with second-degree manslaughter in the death of Harris, 44, on 2 April. Bates was released on bail.
The incident was the latest in a series of fatal shootings of black men that have fuelled a national debate about police use of lethal force, especially against minorities.