Should I talk to the police or investigating agency?

If you called them because of an emergency, yes. But if they are investigating a crime and you are the suspect, no. First, you have the right to be left alone by police and they can't force you to talk to them. You are not violating any law by refusing to answer questions or speak with them about an investigation. Second, giving a statement creates opportunities for the police to misunderstand. Often, they have already decided you are guilty and nothing you can say will help you, in fact, it can be used against you and most often is. It is not up to the police officer to decide if charges will be filed against you. It is the officer’s job to gather information and turn it over to the prosecutor who then determines if there is enough evidence to bring charges against you. Therefore, speaking with the police only provides them with more information to turn over to the prosecuting attorney. Why take the risk?
If you are contacted by police or an investigator who wants to speak to you about a crime in which you are a suspect, call an attorney before speaking to anyone.