The Ankara polis have a well organized and helpful website in English. On it is a history of the police, declarations of the position of the polis and information about crime in Ankara.
Most importantly however, they have an extensive section for foreigners pertaining to visas and laws surrounding being in the country. Also, if you have witnessed or been a victim of a crime, there is an online service where you can report it.
The link to the foreigner section is: