CLEVELAND, Ohio -- An arbitrator halved the suspension Cleveland police officer Frank Garmback received for his role in the fatal shooting of 12-year-old Tamir Rice.

Garmback's original 10-day suspension was reduced to five days by arbitrator Daniel Zeiser of Cleveland. Garmback was previously suspended for using improper tactics when driving his police cruiser to within feet of Tamir and for failing to notify dispatchers when he arrived at Cudell Recreation Center.

Zeiser wrote in his April 4 opinion released to cleveland.com Tuesday as part of a public records request that the city incorrectly put Garmback's disciplinary proceedings in the most serious disciplinary category -- called the Group III category.

The Group III category typically includes excessive uses of force or officer's caught stealing on the job, Zeisler wrote.

Zeisler concluded that Safety Director Michael McGrath disciplined Garmback for offenses that didn't merit the most serious form of discipline.

"Employing improper tactics, while not as serious as the conduct listed in Group III, is more than a minor violation and warrants more than a warning," Zeisler wrote.

Garmback drove a patrol car within feet of Tamir seconds before his partner, now-fired officer Timothy Loehmann, jumped out and fired the shots that killed the boy Nov. 22, 2014 outside Cudell Recreation Center.

Garmback was serving as Leohmann's training officer when they went to investigate a report of a "guy with a gun" scaring people outside the recreation center. Tamir had an airsoft replica pistol tucked in his waistband when he was shot, investigators determined.

Zeisler agreed with McGrath's conclusions that Garmback took an improper approach when driving up to Tamir. He wrote that the issues for the arbitration had nothing to do with the shooting, only the discipline for using improper tactics.

"Though reasonable minds can differ on this point, the Arbitrator concludes there was enough evidence for McGrath to conclude the Grievant employed improper tactics," Zeisler wrote.

McGrath testified that as a training officer, Garmback should have known to wait for back-up, especially because Loehmann was still training. McGrath found that Garmback's conduct "escalated the situation unnecessarily, exposed both him and Loehmann as well as Rice to unreasonable risk of harm, and precipitated the fatal shooting," Zeisler wrote.

A Cuyahoga County grand jury declined to bring criminal charges against Loehmann and Garmback in December 2015. Then-Cuyahoga County Prosecutor Timothy J. McGinty recommended that the grand jury not charge the officers after a series of experts hired by his office deemed the shooting "objectively reasonable."

Loehmann has appealed his firing. His arbitration hearing began in January and finished last month. A decision is expected by the end of the year.

Loehmann's ouster from the department was not the result of the deadly shooting, but instead the fact he failed to disclose information on his application to the Cleveland police department. He failed to disclose that he was asked to resign from the Independence Police Department when a supervisor raised concerns about his ability to be an effective police officer, officials said.

The Cleveland Police Patrolmen's Association, the union that represents rank-and-file officers, appealed Loehmann's firing and Garmback's suspension hours after Safety Director Michael McGrath announced the discipline.

Cleveland Police Chief Calvin Williams assembled a panel of city officials, called the Critical Incident Review Committee, to review the officers' actions during the incident. The review, which took the place of a normal internal affairs investigation, found that neither officer violated any police policies. The panel recommended no discipline.

Williams, however, also asked for a review of Loehmann's employment background, which turned up information about his departure from the Independence Police Department.

The CPPA has argued that Loehmann never intended to lie on his application, but instead simply ran out of room to include his entire employment history.

The city has since changed its policy to review all personnel files for prospective employees who were police officers in other cities.

The city settled with Tamir's family for a record $6 million.

Tamir's mother, Samaria Rice, previously said she was happy Loehmann was fired, but disappointed at the city's reasoning. She also said she was disappointed that Garmback's discipline wasn't more severe.

Two others have also been disciplined in connection with the incident: 911 call-taker Constance Hollinger and officer William Cunningham.

Cunningham had been working off-duty at the Cudell Recreation Center without permission, officials determined. He received a two-day, unpaid suspension.

Hollinger received an eight-day, unpaid suspension for failing to relay critical information to Beth Mandl, a dispatcher who sent Garmback and Loehmann to the recreation center to investigate a report of a "guy with a gun" scaring people outside the center.

Hollinger did not tell Mandl that a 911 caller told her that Tamir was "probably a child" and the airsoft gun was "probably fake," officials said.

Mandl later resigned.

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