The man known as "Whistle" Willis was a pickpocket and an accomplice of Roach. Willis typically wore a bowtie and cloth cap. He had a habit of whistling, hence his nickname. "Whistle" Willis was one of several members of Roach's gang of pickpockets who paid the political "fixer" known as Shoulders to protect them. After Roach attracted the attention of Dick Tracy, Willis and Roach attempted to assault Tracy. Tracy was prepared for the ambush, and both Roach and Willis were taken into custody.