Indeed. I've recently had an issue along those lines albeit on a lesser scale as a witness. The police were more interested in securing a good case for the CPS than actually fairly evaluating the situation. I was actually advised that my statement should only refer to the facts which were likely to aid a conviction rather than be a fair and balanced account of what happened. The moment a conviction was not obviously going to happen, they recommended that I withdraw my statement before they submit the case to the CPS.

I wrote an addendum sheet for the statement instead stating that they'd asked me to do that. That didn't go down well so I better move to another area if I want any policing or assistance in the future...

For ref, no-one was hurt other than insurance companies in this case. Two idiots bounced a car off each other at 20mph - neither need prosecuting.