El Capitan TheatreFormer ER star Maura Tierney is in negotiations for the lead in ABC’s new legal drama The Whole Truth, a role left vacant after the recent departure of Joely Richardson. Tierney, who had to pull out of NBC’s dramedy series Parenthood last fall while undergoing breast cancer treatment, was originally approached for the role in the Jerry Bruckheimer-produced The Whole Truth during pilot season when she fielded multiple offers. After taking a medical break, Tierney recently returned to acting, rejoining FX’s Rescue Me where she has had a recurring role. The Whole Truth, on which she would star opposite Rob Morrow, would bring Tierney back at  Warner Bros. TV, the studio behind ER, on which she starred for 9 seasons. The Whole Truth, which chronicles the way a case is built from the perspective of both the defense and prosecution, is slated to air Wednesdays at 10 PM this fall. Richardson departed the project after the pilot citing personal reasons.