You get four stars and 16 minutes of wanted level when you kill a civilian, a taxi driver, a hooker, a medic, a firefighter or an ARPD officer.
You can also get two stars when an officer suspects you twice.
Re-read my post please. This time, pay attention. Or maybe an example will help:
You're wanted for 30 mins. You evade and it goes down to 6mins. Your stars get reduced a certain number. Well, at least thats what happens to me.
Just note that I'm not sure of the exact time limit etc. and those numbers are just examples
