Video cameras captured the confrontation and assault from the afternoon of November 12, 2013. Officer Charles Pickard removed his gun belt, placed his weapon on the floor and took off his bullet-proof vest. A short time later, Pickard knelt down and appeared to pray. He then stood up and decked the teenager.
Pickard, who was a school resource officer, told investigators he thought the 17-year-old student had marijuana, which turned out to be a false assumption.
A judge found Pickard guilty of second degree assault, misconduct in office and reckless endangerment.
"It's not acceptable. We don't teach that. He lost his temper apparently. But it's unacceptable and won't be tolerated on this police department," said Prince George's County Police Chief Mark Magaw.
"What in our mind is most egregious about the assault in this case is that it occurred in the school," said Prince George's County State's Attorney Angela Alsobrooks.
The judge said the teenager was doing absolutely nothing to warrant the punch. The victim, now an 18-year-old high school senior, spoke to FOX 5's Bob Barnard outside the courtroom.
"And I want to just thank everybody for believing in me and helping me try to get through this. I couldn't do it alone," the student said.
Officer Pickard will be sentenced in July.
MOBILE USERS CLICK HERE FOR PHOTO GALLERY