The trick to the Screamer was that if he saw you, you had a moment to kill him before he ran away. You knew when he was around because of his crazed, maniacal cackling. ' The Screamer was a boss zombie who didn't have any actual attacks he was bound in a straightjacket. Impressively, we don't have to speculate as to what it did, as the developer commentary explains exactly how he worked and why he was cut! Thanks, Valve. There's an unused piece of concept art in the game for a 'Screamer' special infected.
