More U.S. police charged with murder, manslaughter in 2015

CHICAGO -- The number of U.S. police officers charged with murder or manslaughter for on-duty shootings has tripled this year -- a sharp increase at least one expert said could be the result of more video evidence.

In the past, the annual average was fewer than five officers charged. In the final weeks of 2015, that number has climbed to 15, with 10 of the cases involving video.

"If you take the cases with the video away, you are left with what we would expect to see over the past 10 years -- about five cases," said Philip Stinson, the Bowling Green State University criminologist who compiled the statistics from across the nation. "You have to wonder if there would have been charges if there wasn't video evidence."

The importance of video was highlighted last week with the release of footage showing a Chicago officer fatally shooting a teenager 16 times. The officer said he feared for his life from the teen, who was suspected of damaging cars using a small knife. He also had a powerful hallucinogen in his bloodstream.

"This had all the trappings of a life-threatening situation for a law-enforcement officer -- PCP-laced juvenile who had been wreaking havoc on cars with a knife," said Joseph Tacopina, a prominent New York defense attorney and former prosecutor who has represented several police officers. "Except you have the video that shows a straight-out execution."