Who can solve the logical reasoning problem of "solving the crime scene"
Let's assume that A is telling the truth, then we can rule out A, and at the same time know that BCD lied, B lied that D can be ruled out, C lied that B can be ruled out, D lied that B didn't frame him, that is, D was a criminal, so there was a contradiction. So we assume that A is telling the truth and wrong, which means A is lying, which means A is a criminal.