Mekhi Phifer Mekhi Phifer

Just as ER prepares to tee up its series finale, one of its alumni has booked a meaty new gig.

Mekhi Phifer, who for six seasons walked the halls of County General as Dr. Gregory Pratt, has booked a multiple-episode appointment on Fox's Lie to Me, has learned exclusively.

Phifer will appear on the freshman drama series as Ben Reynolds, an FBI agent who partners with Dr. Lightman (Tim Roth) to track a serial rapist terrorizing the D.C. area.

Reynolds serves as The Lightman Group's government liaison on the case, as he has spent six months pursuing the elusive criminal.

Phifer's arc kicks off Wednesday, May 6.

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