Johannes Mehserle, a San Francico area transit cop, shot an unarmed, already searched and subdued man, 22-year-old Oscar Grant, in the back on New Year's Day. He was caught on video doing it. The several BART cops on the scene had been breaking up a fight between two groups of young men and were wrapping up the arrest process when this happened. This received national attention, produced riots and has spawned a lawsuit and a criminal investigation.
Mehserle has now resigned from his job. He was under threat of termination in any case for exercising his 5th Amendment right to refuse to talk to investigators at his lawyers advice. While a decision to exercise your 5th Amendment right not to incriminate yourself with your own statements may not be used as evidence that you committed a crime, it can be held against you in civil matters like lawsuits for money damages and employment hearings.