The police are trying to accomplish at least two objectives in the "information gathering" (pre-arrest) phase: 1. Figuring out what happened here, broadly. If

The police are trying to accomplish at least two objectives in the "information gathering" (pre-arrest) phase: 1. Figuring out what happened here, broadly. If you didn't do it, it truly seems like a good idea to help them with this function. It's easy to conceive of a situation where talking to them can help you here. 2. Collecting information to enable them to charge and testify against someone with. You really don't want to help them with this phase if the someone is you. Which it is. It's much better to deal with this area in court, where you get to see/evaluate/challenge their evidence before making statements. The problem with talking to the police in this pre-arrest phase is that you don't know what objective they're trying to achieve. Truth is, they don't either. They get to decide retroactively if something you said to them at this phase will be used as evidence against you, as evidence against someone else, or just discarded. Worse: in the US, what you said to them can never help you in court. "He told me he was at the scene of the crime" will help convict you, "He told me he he wasn't anywhere near the scene of the crime" will be thrown out as here-say. Given this situation, hindering objective #2 outweighs helping objective #1.