Mayor Rahm Emanuel said he was “saddened and sickened” by the killing of Amari Brown and his father’s reported lack of cooperation with detectives. “You have too many guns on the streets. You have a criminal-justice system that lets out too many people repeatedly who use guns. You have a father who’s lost a child that should be cooperating with the police department in solving the crime of their child. And you have gang-bangers without any moral compunction — without any moral remorse or responsibility shooting into a playground or shooting into a front yard as if it’s their personal shooting gallery,” Emanuel said. “From the criminal justice system to elected leaders as it relates to gun laws . . . to raising people with values, the adults have let . . .  Amari Brown down,” he said.