He knew that Crouch and he couldn’t have done this, because Charis Crouch and his mother, Dorea Potter, back then, when Sirius Black II was alive, forced the two women to sign a contract that neither him nor Crouch Sr. would inherit the Black family title. Harry was able to inherit, because Arcturus Black announced him heir before the old Lord Black retired, but his son with the replacement bond abandoned his duties as heir Black and the title would be given to another member. Bartemius’ son was in Azkaban and was stripped from inheriting the title. So, neither of them was responsible.