Go straight to the HR Department, inquire there, do you have a vacancy. Most likely, the job will really be. Then you can move on. By the way, if you have a legal education, will support you in the personnel Department, and further the process of adoption in valorous ranks of the police will be faster. If legal education is not, rely only on his desire.
You most likely will be offered the position of investigator or inspector on Affairs of minors. It's not sugar, but at first can't be choosers. Why settle for what is offered.
Then you have come the medical. This is the most difficult and tedious part of the whole process. Doctors usually picky, rude, demanding inquiries especially. But that's okay. Be patient and radiate goodwill. If the first time does not have passed some of the doctors, ask and assure that you would pass in the near future. Otherwise, your medical record will close.
In the queue examined by a psychologist (SWC), which will give you the tests which requires a clear answer "correct" or "incorrect". You need to be very careful, as the issues can be a trick. After the psychologist you will be training. You for 3 months will be sent to the police school, will pay travel. When you successfully pass training, you will become a full-fledged police officer. A legal education will provide you with the rank of officer.