The desk sergeant is a holographic San Francisco policeman in the Dixon Hill programme who tries to chat up Beverly Crusher while Picard is being questioned.
The desk sergeant appears in The Big Goodbye. He mans the front desk of the police station to which Dixon Hill is brought for questioning over the murder of his client Jessica Bradley.
While Picard is held in an interview room, Beverly Crusher, Data and the historian Whalen wait outside in period costume. The sergeant takes a liking to Crusher and tries his luck, while she, new to the period, struggles with a compact and a stick of chewing gum.
The scene is a light interlude before the holodeck malfunctions. Soon afterwards Whalen is shot by one of Cyrus Redblock's men, and the visitors discover that the safeguards have failed and the exit will not open.