EXCLUSIVE: Supergirl star Melissa Benoist has joined the cast of Patriots Day, the CBS Films and Lionsgate pic about the events surrounding the Boston Marathon bombing. She’ll play Katherine Russell, the wife of bomber Tamerlan Tsaraev.

Jake Picking Khandi Alexander 2-shotTwo others also have joined the pic: Treme and CSI: Miami alum Khandi Alexander and Jake Picking (Goat). She will play a law enforcement interrogator, and he  is Sean Collier, the MIT police officer who was shot to death after the bombings.

Production is under way in Boston on the pic, which also features Mark Wahlberg, Kevin Bacon, John Goodman, J.K. Simmons, Jimmy O. Yang, Vince Curatola, Michael Beach and James Colby. Bridge of Spies Oscar nominee Matt Charman penned the script. Scott Stuber, Wahlberg, Hutch Parker, Dylan Clark, Stephen Levinson, Dorothy Aufiero and Michael Radutzky are producing. CBS Films is handling production and advertising for Patriots Day, which Lionsgate plans to release in the late-awards-season sweet spot of December 21.

Benoist plays the title superhero in CBS’ freshman drama Supergirl, which is awaiting word on a pickup for Season 2. She co-starred on Glee for three seasons and next appears in the East L.A.-set Lowriders, from Universal Pictures, Blumhouse and Imagine Entertainment. Benoist is repped by UTA and Anonymous Content.

Alexander, who also appeared on Scandal, is repped by Green & Associates. Picking, whose credits include the feature The Way Way Back, is with Innovative Artists and Management 36o.