Billy was born in 1960 and joined the Beverly Hills Police Department in 1981. A good cop, Billy is known to go strictly by the book, and is not as tough as his partner, John Taggart. In the first film, he was generally polite and bumbling, and not particularly competent at anything, until it was revealed toward the end of the film that he had excellent marksmanship with a pistol. The second film expands on this, showing Rosewood having and using excessive firepower and weaponry, as demonstrated by the line: "Billy, we gotta talk."