More than 100 protesters marched through the streets of downtown Decatur for about an hour Wednesday night to call attention to DeKalb County’s second police killing in three months, which they contend was an unjust use of force.

They marched, sang, banged a drum and chanted phrases, including “Hey hey, ho ho, these killer cops have got to go,” and, “Who do you protect? Who do you serve?”

The demonstration went off peacefully, although some motorists who were stopped for extended periods to let the protesters through blew their horns in frustration.

On Monday, DeKalb Officer Robert Olsen shot a 27-year-old Air Force veteran to death who was unarmed and naked outside his Chamblee apartment complex.

DeKalb Public Safety Director Cedric Alexander said the man, Anthony Hill, ran at the officer and ignored warnings to stop during an apparent mental health breakdown.

An email announcing the protest read, “Anthony was naked and unarmed at the time of the shooting, yet Officer Olsen found him to be enough of a threat to take his life.”

Many of the protesters who gathered in the square before the march wore purple, reportedly Hill’s favorite color.

Handmade signs were placed around the area, along with photos of Hill at various stages of life.

One sign read: “Anthony Hill fought for his country only to be murdered by a DeKalb police officer. Demilitarize the police.”

Justin Grant, who described himself as being best friends with Hill, called him “a loving person, a great person. Everybody around him loved him. He smiled every time you saw him.”

Grant said, “I’m just happy that he’s changing the world already. That’s what he wanted. He wanted the world to know that all lives matter. Not just black, not just white, everybody.”

Organizer Jim Chambers said his goal Wednesday night was to honor Hill and begin a discussion of the issue in the community.

Another case was also on the crowd’s mind.

In December, Officer Joseph Pitts shot Kevin Davis, a 44-year-old man who had called 911 for help, after killing his dog.

Alexander said Pitts shot Davis after he didn't drop a gun. Davis was demanding to know why the officer had shot his dog but was not pointing the gun at Pitts, Alexander said.

Davis, who had no arrest record, had come to the door after hearing the gunshots believing a man who had assaulted his girlfriend had returned, Alexander said.

The Georgia Bureau of Investigation is investigating both cases at Alexander’s request.

Outrage at the killing of both men was driven by social media in the aftermath of the shootings.

Last year, the public, activists and some state legislators began pushing for more restraints on police use of force following a botched raid in Habersham County that resulted in a stun grenade seriously injuring a toddler. Last July, Neighbors and family members of a mentally ill woman in Henry County also voiced anger after police shot her in her home after she would not drop a pistol during a psychotic episode. Her husband who had called police warning that his wife was having a mental breakdown had warned them not to enter the house until he got there.

—Photographer Ben Gray contributed to this report.