Christopher Alexander Ridley was 23 and an off-duty Mount Vernon police officer when he was killed on January 25, 2008, near Court Street and Martine Avenue in White Plains, New York. According to accounts, he intervened in an altercation between two homeless men and was attacked. During the struggle his handgun fell and discharged. Two nearby Westchester County police officers heard the shot and, not realizing Ridley was a fellow officer, ordered him to drop his weapon. When he did not immediately comply they opened fire and fatally wounded him.

A grand jury declined to indict the two Westchester County officers involved. Ridley was posthumously promoted to Detective. His family filed a federal civil suit alleging wrongdoing; a jury later found the officers not liable. The shooting prompted discussions about procedures and led to changes in use-of-force training and protocols. A memorial was placed at the shooting site.