Why is Ralph by a suspect?

Ackroyd’s stepson, Paton is handsome and charming, but constantly getting into trouble with debts and financial obligations. His disappearance, as well as several major clues (including how well he stood to benefit from Ackroyd’s death), make him the major suspect in the crime. He is described as having a “weak” character, which leads him to fall constantly into debt, and look for easy ways to discharge it (such as agreeing to marry Flora when he is already committed).