With ER going off the air for good tonight, one of its former cast members has landed a new gig.

Mekhi Phifer, who played Dr. Gregory Pratt on the NBC drama for six years, has booked a multiple-episode arc on Lie to Me.

Look for Phifer in the role of Ben Reynolds, an FBI agent that partners with Dr. Cal Lightman (Tim Roth) to track a serial rapist in the D.C. area.

Reynolds will serve as The Lightman Group's government liaison on the investigation. When he comes aboard - on May 6 - the character will have spent the previous six months pursuing the criminal.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.