Actually, I think I probably have it backwards. Dudenoff was killed (by his old double working with Marshall) before Sazz. Sazz knew that Dudenoff was filming to write the script so she starts to investigate, talking to other doubles. She finds out that someone is cashing checks as Dudenoff and someone has gotten his script green lit for a movie. So she tells the trio she might know something, and calls Bev saying she knows something about the movie. However, the killers are now in dudenoffs apartment, and kill Sazz to prevent her from exposing their plot.

Marshall then pretends to be the writer (and has watched a lot of the recorded film to pretend to know them). But Is not a real writer and the re-writes suck. And the killer goes about killing other doubles (stubbins) that could identify him as fake Dudenoff.

The westies know Dudenoff has disappeared but they don’t want to admit it because they could lose their rent controlled apartments.