Sweet Hereafter director Atom Egoyan’s West Memphis Three drama Devil’s Knot is about to start shooting and has made a few new additions to its cast. Collette Wolfe (pictured above; Young Adult), Kris Polaha (“The Ringer”) and Justin Çastor (“Glee”) have joined the cast.

Per Deadline, “Kris Polaha will be playing public defender Val Price in the movie about the conviction of the West Memphis 3. Collette Wolfe has joined the film as Firth’s character’s assistant Glori Shettles. Justin Castor is talks to play James Baldwin, one of the WM3.”

The pic is based on investigative reporter Mara Leveritt’s 2002 book “Devil’s Knot: The True Story of the West Memphis Three,” which chronicled the prolonged murder trial of defendants Damien Echols, Jason Baldwin and Jessie Misskelley Jr., who served 18 years in prison before being released in August. The trio were accused of killing Christopher Byers, Michael Moore and Stevie Branch, three 8-year-old boys who were found brutally murdered and hog-tied in a wooded area of West Memphis, Arkansas known as Robin Hood Hills.

They join recent addition Kristopher Higgins. The film stars Reese Witherspoon (Freeway, Legally Blonde) as Pam Hobbs, the mother of one of the victims. Hobbs originally believed that Echols, Baldwin and Misskelley murdered her son, but as the case dragged on and more details became available, she came to believe that the trio did not commit the heinous crime. Colin Firth (A Single Man) will also star.

Mark Sevi wrote the original draft of the screenplay, with the current draft penned by Scott Derrickson (whose Sinister has some really great scares) and Paul Boardman.