Testimony before the U.S. Commission on Civil Rights, Briefing on Police Practices and Use of...

"According to an investigation of New York City’s Civilian Complaint Review Board records, about 40 percent of the 35,000 NYPD officers have never received a civilian complaint, but roughly 1,000 officers have more than 10 complaints on file. One officer has over 50 complaints but retains his position.
Those 1,000 officers represent fewer than three percent of NYPD officers but can damage the reputation of the rest of the department."
I am sure it is much the same across the rest of the country. A way has to be made to identify and deal with these "bad apples" before we have any more tragedies that didn't have to happen.