You are mistaken as to Dr. Lalezari. He was merely

You are mistaken as to Dr. Lalezari. He was merely an Acting CMO and then an Acting CSO. He never left, his term expired when the permanent CMO, Scott Kelly, was hired, and then later his term expired when the permanent CSO, Rahman, was hired. I would not be surprised if Lalezari came back as Interim CSO again now that there is a vacancy again.