But lawyers are expensive, and if it turns out you are just a witness, you are going to be spending a lot of money for nothing.

And then consider if you are are the spouse or parent of a murder victim or missing person, and are innocent. You are almost certainly going to be a potential suspect, but you also want to help them find the actual criminal, and if hiring a lawyer makes you "look guilty", then the police might focus their investigation on you rather than finding the real perpetrator.