CHICAGO (CBS) — The mother of a 12-year-old Cleveland boy who was killed by police last year was in Chicago on Friday, for a series of meetings, marches, and protests about alleged police misconduct.

At her press conference at City Hall in Chicago on Friday, Samaria Rice was asked what she hopes to accomplish in Chicago.

“I really just want justice for my son, and justice for all,” she said.

A Cleveland police officer shot and killed Rice’s 12-year-old son, Tamir, on Nov. 22. Police were responding to a call about a person with a gun outside a city recreation center, and saw Tamir holding what turned out to be a pellet gun. The officers reported Rice reached toward a gun in his waistband, and shot him in the chest. He died the next day.

Prosecutors are reviewing a sheriff’s department investigation into Tamir’s death, and will decide if criminal charges should be filed against the rookie police officer who shot Tamir. The shooting helped spark growing racial tensions regarding police treatment of African Americans; Tamir was black, and the officer who shot him – patrolman Timothy Loehman – is white.

Her lawyer, Billy Joe Mills, said police respond to conflict with violence, rather than love.

“That psychology and mentality trickles down into the minds of young people,” he said.

Rice showed up at City Hall with a number of activists – from Amnesty International, to those trying to stop violent crime, to those who think police are nothing more than murdering thugs.

“The police will murder any and everyone,” said Otis Buckley, of Total Blackout For Reform. “White, black, or brown; they do not care,” one activist said.

Others in the group were a bit less inflammatory. Rosa, an activist with Black Youth Project 100, said those who police the police aren’t doing it.

“Four hundred investigations, and only one found unjustified,”

Activist Mark Clements, who spent 28 years behind bars for murder before he was exonerated and freed in 2010, said people need to stop killing each other.

“Nothing’s inside of a prison cell but pain,” he said.

At the same time, Clements noted the city reportedly has paid out more than half a billion dollars over the past decade on police brutality-related lawsuits – including settlements, judgments, legal fees, and other expenses.