No, you do not have to return the detetive's call. You don't even have to speak to him if he shows up to your home or asks you to come in to the police station. The fact is that, law enforccment is trained to try and get a suspect to incrimnate themself. They are quite skilled at this. They can do so through intimidation or by playing the "good guy"card and acting as a concerned friend. So stay away from them and don't put yourself in that position. What you should do now is to consult directly with a criminal law attorney. They can best advise you further. Whatever you do, do not speak to the police, at least not without legal reprentation.