"If you do the job in a way that disrespects the badge that you hold, I will see to it that you're either removed from police service, or further prosecuted," he said at his swearing in ceremony.
Moss, a 32-year veteran of Miami's police department, has experience with troubled agencies. He was a teenager in Miami during the violent 1980's when he says he was harassed by police.
"He was a white police officer, and he told me 'You n-word, don't walk downtown after dark,'" Moss told CBS News. "I had another experience not long after that, the police officer gets out of the car, pushes me up against the wall, he starts to frisk me."
Why would that draw him to law enforcement, rather than push him away? "My grandmother has a saying, and that is you can't clean a house if you're not in it."
A Justice Department investigation found between 2012 and 2014 in Ferguson, every person taken into custody for resisting arrest after a traffic stop was African American.
Fred Watson's case was in the DOJ report. Four years ago as he was sitting in his parked car, when a Ferguson police officer demanded his ID.
"I reached to get it from the back, in my pocket. He said put your hands on the wheel," said Watson. "He pulled out his gun, telling me to get out of the car."
Watson's case is still not resolved.
Moss says he will hold his officers to a higher standard. "I expect to clean house where I find that people need to go."
But Moss knows that a new police chief is just one step toward real change in Ferguson.