Trivia: Alison Lohman, who plays Nicolas Cage's teenage (14) daughter, is actually 24.
Trivia: The 4 main characters (Roy, Angela, Frank and Frechette) all smoke at some point in the film. This is a clue added by the filmmakers to indicate that the people who smoke in the film are con men, a teaser if you like to indicate that Angela is also involved in the con (This is revealed in the DVD director's commentary).
Trivia: Frank Mercer is the combination of John Mercer and Frank Sinatra, whose discs are played by Ron Waller throughout the movie.
Answer: They needed to get the password for Roy's safety deposit box. They planted the camera and microphones so that they could listen in on the conversation and know what the password is.
Casual Person
But he gave the code to the doctor who was in on it.