A top sheriff’s official resigned on Monday in Tulsa, Oklahoma, where an unarmed man was shot and killed earlier this month by a volunteer reserve deputy who says he mistook his gun for his Taser.

Sheriff Stanley Glanz announced the resignation of Tim Albin, the undersheriff. A 2009 internal review obtained by NBC News found that Albin had asked employees to modify reviews and training documentation for the volunteer deputy, Robert Bates.

RELATED: Colleagues questioned Robert Bates years before fatal shooting

The same review found that Albin told people who raised concerns about Bates to keep their mouths shut.

The sheriff said he accepted the resignation “as we look as a community for answers to the situation which put Mr. Bates and Mr. Harris on that fatal path.”

Bates shot and killed Eric Harris, a suspect in an undercover gun sting, on April 2. Bates has pleaded not guilty to second-degree manslaughter. In an interview on TODAY earlier this month, Bates said the shooting was the biggest regret of his life.

Just a week ago, Albin spoke during a news conference where Glanz deferred to him several times to answer questions from reporters.

This article originally appeared on NBCNews.com.