ALGOMA TOWNSHIP, Mich. (WOOD) — A deputy was justified in the fatal shooting of a man following a domestic altercation, the Kent County prosecutor has decided.

In a report released Tuesday, Prosecutor Chris Becker said Kent County Deputy Jason Wiersma was trying to protect the man’s brother when Wiersma shot and killed Jonathan David Sper on Jan. 24.

>>PDF: Prosecutor’s report on Sper shooting investigation

According to Sper’s family, Jonathan had been undergoing mental health treatment for years for severe mental illness. He was diagnosed with bipolar disorder at 18.

“I don’t think Jonathan would have done what he did if not for his mental health,” Becker told 24 Hour News 8 on Tuesday.

Deputies were initially called to a home in the 4000 block of Summit Court NE in Algoma Township for a dispute between Jonathan and his brother Stephen.

Stephen told deputies he had locked Jonathan in the garage after Jonathan attacked him. He said his brother was in a “manic state” and had a history of mental health issues.

When deputies tried to place Jonathan in handcuffs, police say he violently struck Deputy Wiersma multiple times and a struggle ensued. Wiersma and Jonathan then fell down a flight of 15 stairs.

According to police, Jonathan continued hitting the deputy, who then used a Taser, but both attempts were unsuccessful.

Another deputy tried to help his partner but was stabbed, possibly with a bottle, by Jonathan.

As Jonathan made it up the stairs and into the home, Wiersma ordered him multiple times to drop the sharp object that was in his hand. However, after the shooting occurred no weapon was found around Jonathan, although there were some keys next to the door.

Deputies were also under the impression that Jonathan had accessed a gun from a truck and was under the influence of drugs and alcohol, according to his brother’s statement. A later toxicology report showed Jonathan had a blood alcohol content level of .08 percent.

Prosecutor Becker said this all led up to the deputy’s decision to shoot Jonathan to stop him from attacking his brother again.

“That’s the option he chose, and I can’t say it’s not justified by doing that,” he told 24 Hour News 8.

Becker said in the release that the effects of Jonathan’s severe mental illness combined with the consumption of alcohol led to his violent behavior the night of the shooting. He called it a “complete tragedy for everyone involved.”

“This is a tragedy for the Sper family. It’s a tragedy I couldn’t imagine,” Becker said.

Sper had been released from the Kent County jail the same day he was killed after failing to pay his dinner bill at a downtown Grand Rapids restaurant.

Becker says prisoners with mental health problems are among the issues that county courts and law enforcement hope to address with a new Crisis Mental Health Team. Becker says that might have made a difference in this case.

“This is very speculative, but conceivably … instead of having him sit in the jail, maybe we get him into treatment,” Becker said. “Maybe we get him somewhere where he gets help and isn’t just released. So I think it should  have had some benefit.”

That program is expected to be rolled out sometime this spring.

The deputies involved were placed on administrative leave after the incident, which is standard procedure as it was investigated. One of them is already back to work. Wiersma is expected to be back on the job next week.

–24 Hour News 8’s Joe LaFurgey contributed to this report.