(from left) Boston Police Commissioner Ed Davis, Mayor Thomas Menino and police Capt. Patrick Crossen unveil a memorial to Boston Police motorcycle officers killed in the line of duty at the unit’s Roxbury headquarters Sept. 16. One of six officers, Patrolman William Abbott, was killed in Mission Hill, where a historical signs in his honor was decorated with a memorial wreath during a motorcycle tribute ride earlier in the day. (Photo Courtesy Mayor’s Office)