Cleaned the Mean Streets

"Use the computer in a police car to "View Current Crimes" and kill 20 criminals."

- In-game description

Cleaned the Mean Streets is an achievement/trophy in Grand Theft Auto IV.

Acquisition
Find any police car and stop to access the police computer. Go to "View Current Crimes". Choose any active crime and kill the criminal involved to complete it. Repeat 19 more times and the achievement/trophy will be unlocked.