If C is telling the truth, A is lying, and that A is a criminal, but C says D is a criminal, then C is also lying.
If D is telling the truth, then C is lying, then D can be ruled out as a criminal, and A B C may be a criminal.
The first reason is that B and C are lies.
The second reason is that both A and C are lies, so D is not a criminal, so D is excluded.
From the first two reasons, A B C is deceptive, while D says that B sets himself up and A is deceptive, so A and B may be suspects.
The topic is too limited, and it can only be calculated that A or B is the suspect and D is the truth.