A U.S. attorney responsible for putting mortgage fraudsters in jail has warned that lenders need to tackle a subculture of corruption in the industry and to be careful about the signals that they are sending to would-be wrongdoers. “You have to change the culture,” said Michael Blume, a prosecutor with the U.S. Attorney’s Office in Philadelphia, during a panel discussion on fraud at the recent Non-prime and Alternative Products Conference, sponsored by the Mortgage…