Grand Theft Auto IV Walkthrough

Now, it's important to have something like an Uzi equipped even before that cutscene occurs, because the goon will run off as soon as you gain control, and you'll have to run after him quickly, which won't give you an incredible amount of time to toggle between your weapons. Run up the stairs in pursuit of the foe, and you'll hear him take off on a scooter. You'll have to do the same, but before you do, point your weapon at him and fire at him. You won't take him down, but you will diminish his health significantly, making your life easier later.

Give chase with a nearby scooter. It won't be high speed, obviously, because the scooters can't reach top speeds, but you'll have to keep a close eye on your HUD, because your enemy won't be using roads. He'll be using paths and parks and all sorts of other things. When he starts to slow down and talk to you (telling you to leave him alone), that's your cue to put the final few bullets into him, ending his life. However, you likely managed to get some cop attention at this point, so be sure to lose them as you head to southern Algonquin, where Bernie wants to be dropped off at the Perseus high-end clothing store on Amethyst Street.