Mr. Bowles is the husband of Susan Bowles and the father of Jeremy and Emily Bowles. He makes no appearances throughout the game.
Susan tells Scott Shelby about her husband when his investigation of the Origami Killer brings him to her house. She states that he left the day after Jeremy disappeared without telling her anything or leaving a note. Losing both her son and her husband and having to take care of her daughter alone left her feeling so overwhelmed that she tried to commit suicide. Before Scott leaves, she gives him the cell phone that her husband left behind.
What happened to Mr. Bowles after he left his family is unknown, though Jeremy's death implies that he failed to complete the trials. The body that Ethan Mars may discover while crawling through the tunnels during "The Butterfly" is most likely Mr. Bowles' body, as corroborated by a behind-the-scenes video.