Westchester County legislators have unanimously approved a permanent memorial to honor a Mount Vernon police officer who was shot and killed a decade ago in White Plains.

Christopher Ridley was a 23-year-old rookie officer who was off duty and in street clothes when he tried to break up a fight and was shot by four county police officers in January 2008.

The officers and witnesses at the scene maintained that Ridley never identified himself as an officer. The fatal shooting prompted special training for police when confronting off-duty officers.

The plaza outside 85 Court St. has been renamed in Ridley's honor. Legislators approved $150,000 for a memorial there.

A federal grand jury found the officers not liable in Ridley's death.