If the answer is yes; demand to have your attorney present. Don't be afraid to ask. "Am I the target of a criminal investigation?" Just saying it mkaes the point. Once you acknowledge to yourself that you might be the target, even if the investigator says otherwise, it's much easier to say, "I cannot answer any questions without my lawyer being present".
2. Are you being questioned after having been arrested?
If you have been arretsed or "detained", you are the target of a criminal investigation. Do not fool yourself. Demand to have your lawyer present!
3. Is someone calling you on the telephone and accusing you of Wrongdoing
This is often called "a telephone sting"; and yes, you are being secretly recorded! An allegation is made to the police. Many times, the police will enlist the assistance of a trusted friend or family member who in turn will unexpectedly call you. The goal is to seek an apology or other form of admission which can then be used against you.
4. Are the police trying to obtain information to "close out a complaint"
This is an old police trick. Of course the investigator knows that the complainant is lying. He just wants to get your side of the story so he can close out the case. This is nonsense. You are the target of a criminal investigation. Anything you say will be used against you. Demand to have a lawyer present.