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Fringe - Episode 4.01 - Casting Call

Here's some info from a casting notice for episode 401:

Director: Joe Chappelle
Writers: Jeff Pinkner, Joel Wyman
Shoot Dates: July 14-July 25
Location: Vancouver

They're casting for the guest role of "Danzig," who is 35 to 45, Caucasian, and an FBI agent with roguish charm.

Source: Rhoswen@TWoP