The head of the dietary supplement maker at the heart of a political scandal involving Virginia Gov. Bob McDonnell is set to resign at the company’s shareholder meeting. Star Scientific Inc. announced last month that CEO Jonnie R. Williams and president Paul Perito planned to step down after Friday’s meeting in Washington, D.C. The Glen Allen, Va.-based company said both will stay on with the company for another year to help with litigation and new product development. Star Scientific makes an anti-inflammatory supplement called Anatabloc. Dr. Michael Mullan is expected to replace Williams. Mullan is the CEO of the Roskamp Institute and Archer Pharmaceuticals Inc. State and federal investigators are looking at whether Williams or his company received anything in return for loans and gifts he gave to McDonnell’s family.