Robert Bates, a 74-year-old volunteer reserve sheriff deputy for the Tulsa County Sheriff’s Office, was found guilty of second-degree manslaughter by a jury on Wednesday. While working for the sheriff’s office last year, Bates shot and killed an unarmed suspect, Eric Courtney Harris, 44 on April 2.

As we have drawn our attention and scrutiny on many high-profile cases since 18-year-old Michael Brown was fatally shot by Ferguson police officer Darren Wilson in 2014, Bates’ shooting of Harris fits the narrative of a white cop shooting a black suspect all too closely.

Harris was the unarmed subject of a sting operation who had attempted to flee after deputies attempted to arrest him for illegally selling a gun.

Bates never denied that he had killed Harris, but has maintained that he didn’t mean to use his service weapon–he thought mistook his gun was a Taser. Charging documents say that as other deputies tackled Harris and held him to the ground, Bates fired his revolver into Harris’ back, while believing it was the stun gun he was holding in his hand.

His defense team claimed it was an honest mistake. After all, Bates could be heard on video claiming he was going to deploy his stun gun before he fired the revolver. After the shot was fired, Bates’ voice is heard on the video saying, “Oh, I shot him. I’m sorry.”

Deputy Leighton Boyd said during his testimony that the heard Bates say he was going to use the Taser and then moved out of the way to avoid being hit by a stun gun.

The prosecution, however, argued that Bates should not have inserted himself into the situation at all. He was along as backup and had been dozing in the car when deputies began to pursue Harris. There were other better-trained deputies holding Harris down when Bates fired the weapon.

Bates’ attorney Clark Brewster also attempted to convince the jury that Harris had not died from the gunshot at all, but rather from a bad heart and mix of drugs in his system.

The jurors in Bates’ trial had been tasked with determining whether the lethal shooting as “an act of culpable negligence.” It took less than three hours for the all-white jury to reach their guilty verdict and recommend that Harris serve the maximum sentence for the crime, four years in prison. The preliminary sentencing hearing will be May 31.

Harris’ death has sparked a civil suit by the victim’s family and national controversy over the practice of using volunteers as law enforcement officers and fears that they are not properly trained. When Harris was shot and killed, Bates was employed as the CEO of an insurance company. He had donated thousands of dollars to the sheriff’s office and had been a reserve deputy since 2008. His most notable training and experience was from the 1960s, when he worked for one year with the Tulsa Police Department.

An internal investigation shows that other deputies were concerned that Bates hadn’t received proper training. They described his behavior in the field as “scary,” but they were told by supervisors to “stop messing with [Bates] because he does a lot … for the County.”

The investigation led to the resignation in November of Tulsa County Sheriff Stanley Glanz and the suspension of the reserve deputy program. Glanz was a fishing buddy of Bates who had accepted lavish gifts from the retired CEO, who had even served as his campaign chairman.

It took a year to bring justice to Harris’ family.

“That’s victory for my family,” said the slain man’s brother Andre Harris. “I can rest. I can have some peace!”