A memorial was held Sunday for a Westchester County police officer who was fatally shot by four officers when he tried to stop a mugging in White Plains.

Hundreds of people mourned Officer Christopher Ridley on the one-year anniversary of his death. He was killed by the officers, who while responding to the mugging mistook him for a criminal because he was off duty and dressed in plain clothes.

County Executive Andrew Spano dedicated 85 Court Street Plaza in Ridley's honor.