A jury on Monday found an Oklahoma City police officer guilty of second-degree murder in the shooting death of a suicidal man who was threatening to set himself on fire. The jury deliberated about five-and-a-half hours before finding Sergeant Keith Sweeney guilty in the November 15, 2017, death of 29-year-old Dustin Pigeon and recommending a 10-year prison sentence. Second-degree murder is punishable by 10 years to life in prison.

Sweeney was among officers responding to reports of a suicidal person. The officers found Pigeon doused in lighter fluid and threatening to set himself on fire in a courtyard.

Prosecutors say Sweeney shot Pigeon after another officer fired a bean bag. An affidavit says Pigeon was unarmed and did not pose a threat when he was shot, and two fellow officers also testified that Pigeon posed no threat.

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Pigeon's father Boston Pigeon told CBS affiliate KWTV at the time that he didn't understand why his son was fatally shot.

"He went out and helped people. He just was not a mean man. He was not," he said. "He was a good person."

This undated file photo shows Oklahoma City police Sergeant Keith Sweeney Oklahoma County Sheriff's Office

Defense attorney Gary James has said that Sweeney didn't know Pigeon was unarmed because the other officers didn't notify him by radio, and that Sweeney made the proper decision based on the information he was given.

But prosecutors argued that Sweeney didn't follow protocol when he shot Pigeon three times, including once in the heart.

District Attorney David Prater said Sweeney "violated just about every policy he could have regarding how you deal with the mentally ill and how you deal with a person when you're trying to de-escalate the situation."