Just days after the Department of Justice announced a civil-rights investigation into the Chicago Police Department, Chicagoans are calling for the resignation of Mayor Rahm Emanuel.On Wednesday, Emanuel offered a public apology to Chicago aldermen for the police shooting of Laquan McDonald "that happened on my watch.""If we're going to fix it, I want you to understand it's my responsibility with you," Emanuel said in a rare speech to the full Chicago City Council, according to the Chicago Tribune . "But if we're also going to begin the healing process, the first step in that journey is my step, and I'm sorry."His apology was met with protests.Hundreds of people staged a citywide walkout, demanding an investigation of the mayor's administration as well as his resignation. They chanted, "Justice," "How many shots? Sixteen shots," "Who's got to go? Rahm's got to go," and "No more killer cops."