Mark A. Sargent resigned unexpectedly as law dean at Villanova University last week. On Friday, police reports emerged identifying Sargent as a customer of a prostitution ring who cooperated with police, leading to the arrest of the man who ran the operation, The Philadelphia Inquirer reported. University officials declined to comment except to say that Sargent would not be returning to the law school's faculty. Sargent could not be reached for comment.