Speaking to TV Guide, Roth explained that his character Cal will sever his ties with the FBI.
"It's much more difficult for him to open doors and get inside places," he said. "So he has to resort to borderline illegal tactics and his own sense of mischief to get into a room.
"All of the stuff with Reynolds [Mekhi Phifer] was good and enjoyable, but it made things too easy for Lightman. Things are much more fun when it's difficult for him to get access. It's much more the rogue element."
However, executive producer Alexander Cary revealed that Cal's new tactics may get him into trouble.
"We are leaning into Lightman's general conflict with power and authority," he said. "In the first episode of season three, he goes too far. He sails extremely close to the wind."
The third season of Lie To Me premieres tonight at 9/8c on Fox.