A former Tulsa reserve deputy who fatally shot an unarmed, restrained suspect after mistaking his gun for his Taser was sentenced to 4 years in prison on Tuesday, the Associated Press reports.

Last month, 74-year-old Robert Bates was convicted of second-degree manslaughter for fatally shooting Eric Harris, whom other officers had already pinned to the ground during a gun sales sting operation. In a video of the shooting later released to the public, Bates can be heard apologizing for firing his weapon while deputies ignore Harris’ pleas for help.

After the shooting, the Tulsa World discovered that Bates, a wealthy insurance executive, had donated thousands of dollars in equipment to the sheriff’s office. Bates later characterized accusations that he was allowed to “play cop” because of his contributions as “unbelievably unfair.”

“You must believe me. This can happen to anyone,” Bates told TODAY. “The laser light is the same on each weapon. I saw the light and I squeezed the trigger and then realized I dropped the gun.”

According to the AP, Bates’ lawyers called the killing an “excusable homicide” during the trial and argued that Harris died, in part, due to poor cardiac health and methamphetamine found in his blood. After convicting Harris, jurors recommended that Bates serve the maximum possible sentence for his crime.

“I’m confident we’ll get a new audience through the appellate courts,” defense attorney Clark Brewster told reporters after Tuesday’s sentencing, “and you’ll be interviewing me about the reversal.”