Murder Sings the Blues

S3, E7: A young woman dies after she starts bleeding from the eyes, nose, and mouth while at a party aboard a subway train. Mac originally believes she is the victim of a biological attack. Later, it is revealed that Sheldon knew the victim. Across town, a wealthy playboy is found dead in an indoor lap pool in his penthouse suite. The investigation reveals that he was murdered and his last maid was fired two days earlier.