if it is possible to say "the real culprit is XY", is it then also possible to say "the real responsible person is XY" when we are not talking about a crime? Because I think that the expression "culprit" may only be used in connection with a crime.
Yes, both are possible, and either are okay. Even though you are not talking about a crime, you can use culprit, because the person responsible was responsible for a bad thing. I would probably use 'culprit' in this case, but its up to you.
EDIT: actually, culprit is used to describe someone who did it intentionally, so maybe not. Prior advice stands.
real? 
Linear Mode
