SPOKANE, Wash. — The U.S. Supreme Court declined to hear the appeal of a former Washington state police officer convicted of using excessive force in the 2006 death of a developmentally disabled janitor he wrongly suspected of theft, a case that helped lead to a federal review of the Spokane Police Department.

The high court issued the denial Monday for former Officer Karl Thompson Jr., who is serving a four-year prison sentence tied to Otto Zehm's death. Thompson's attorneys contended that jurors heard evidence that legally should have been withheld, The Spokesman-Review reported Wednesday (http://bit.ly/1wZOFTP ).

The decision ends a two-year appeals process for Thompson, who is scheduled to remain in a low-security facility in Arizona until July 2016. He was convicted in 2011 of violating Zehm's civil rights by using excessive force and trying to conceal evidence.

Thompson's attorney, Carl Oreskovich, said the decision was not surprising given the large volume of requests the nation's highest court receives. He said he had not yet discussed plans for further litigation.

"It disappoints me, too," Oreskovich said. "I think the system failed."

Local prosecutors initially cleared Thompson of wrongdoing in his confrontation with Zehm, which took place in a convenience store on March 18, 2006. Witnesses reported seeing Thompson strike the 36-year-old janitor multiple times with a baton, shoot him with a stun gun and hog-tie him after Thompson responded to a theft report that turned out to be false. Zehm died a few days later.

But the FBI took up the case and scrutinized much of the evidence, including convenience store video that became a key issue at trial. The video appeared to contradict Thompson's initial statement that Zehm threatened the officer with a Pepsi bottle. The video showed Thompson entering the store and almost immediately attacking Zehm, who was in the store to buy a candy bar.

Thompson was responding to a call that a man had tried to rob a nearby ATM, but Zehm was not involved.

Zehm's death helped prompt a U.S. Justice Department review of the Police Department. The agency is expected to release about 40 recommendations Friday, including using body cameras and better training for dealing with the mentally disabled.

Mike Ormsby, U.S. attorney for the Eastern District of Washington, credited the work of trial attorneys in putting together the case against Thompson.

"The process has taken a long time, but in the end, the interests of justice were served," Ormsby said Tuesday.