You really think this is a language issue? If police officer doesn't bother to find a way to hear the both sides regardless the language they're speaking (it could also be Swahili) then most probably he wouldn't believe to his side of story anyway, even if he could understand him.
Couldn't it be an Arabic/non-Arabic issue?

Well, if the things get this ugly, I believe the only solution is getting a lawyer and not signing anything you don't understand before talking to him.