Knox Ricksen, a civil litigation firm specializing in complex health care fraud cases, has added Mark Heisey as a senior associate in its Walnut Creek office. He joins the firm from Gordon Rees Scully Mansukhani's San Francisco office. With nearly a decade of experience, Heisey has managed cases in a variety of industries through all stages of litigation, including responding to discovery, analyzing liability and damages, negotiating settlement of claims and trial advocacy.