Aaron Castor is a rookie patrol officer in the Western District.
Castor is a rookie patrolman, assigned with Brian Baker to the Western District under the command of Howard Colvin in season three. He and Baker are both ordered by Colvin to carry a compass until they can correctly identify the north direction. He is apparently the nephew of former Baltimore Police officer Lloyd Castor, whom Major Colvin has dubbed as "good police."
In season five Castor is first seen warning his new Major, Dennis Mello, about a brawl in the district parking lot. Later, Castor is the first officer at the triple homicide of Junebug and his wife and associate investigated by Detective Kima Greggs. Castor fails to notice a child hiding in a closet when he secures the scene and Greggs hears the child when she arrives.
Castor is played by Lee Everett Cox. In the third season the actor was credited as Lee E. Cox.