U.S. actor Matt Damon poses for photographers at a photo call to promote the film The Bourne Ultimatum in Tokyo October 18, 2007. REUTERS/Michael Caronna

Josh Zetumer has signed on to pen the fourth installment of the Bourne movie series, writing what is being described as a parallel script to one that was written earlier.

George Nolfi, who worked on The Bourne Ultimatum for Universal, had come back for the fourth entry in the action series. He also signed on to write and direct The Adjustment Bureau, an adaptation of a Philip K. Dick short story that reteams him with Bourne star Matt Damon. But as that movie nears its September start date, Nolfi had to step away from Bourne.

Not wishing to slow development and keen on making Bourne part of its 2011 slate, Universal hired Zetumer to write a new script. It's unclear whether Zetumer's draft will be integrated with Nolfi's.

Our hope is that Nolfi, a key member of the 'Bourne' team, will return after he is done with 'The Adjustment Bureau,' a Universal spokesperson said.

Zetumer's screenwriting credits include Dune, for director Pete Berg and Paramount, and Warner Bros.' The Infiltrator, to which Leonardo DiCaprio is attached to star.