Twenty years ago today Minneapolis police officer Jerry Haaf, 53, was killed in the line of duty, shot in the back as he sat at the Pizza Shack restaurant on East Lake Street. He was a 30-year veteran of the force and months away from retirement.

Four men were eventually caught and convicted for his death, including triggermen Shannon Bowles and Mwati (Pepi) McKenzie. Also convicted on charges that they assisted and planned the killing were A.C.Ford Jr., who later changed his name to Adl El-Shabazz, and Montery Willis.

Hours before the killing, a police-community meeting in north Minneapolis had turned tense when some people accused the Minneapolis police and Metro Transit police of manhandling a blind, disabled black man over unpaid bus fare. Bowles, McKenzie and Willis originally planned to shoot out city bus tires in retaliation, but when they realized that city buses had stopped running, Ford suggested that they hit the now-shuttered Pizza Shack, a well-known police hangout.

The cold-blooded killing shook the city. Media coverage of the slaying and subsequent trials of the four defendants dominated the front page and nightly news casts. A man suspected of cooperating with police, Ed Harris, was killed 15 days after Haaf's death. The Haaf shooting also put an end to an unusual police-gang cooperative agreement in which a group called United for Peace had pledged to work with authorities to end inter-gang violence. Two of the initial arrests in the Haaf killing were made at the home of United for Peace founder Sharif Willis; his nephew was Montery Willis.

Haaf, who was married with three children, was the first city officer to be shot to death in more than a decade. In 2002, Minneapolis police officer Melissa Schmidt was shot and killed in a public housing complex in the Lyndale neighborhood. Minneapolis Park Police officer Mark Bedard was killed In 2007 while responding to a drive-by shooting. He was chasing a suspect on foot when he was struck by a Minneapolis Police Department squad car. He died a week later. A memorial to Bedard was unveiled at Minnehaha Park this spring.