Dr. Mark Knight calls himself an artist, one whose gifted hands" sculpt bodies to perfection. Sometimes, though, Knight's hands strayed. So last year regulators placed the plastic surgeon ... on probation for sexual misconduct with patients. He will be subject to restrictions on his practice and close monitoring until 2020. But when patients come to his office ... Knight doesn't have to tell them about his disciplinary status. And he doesn't have to explain why an extra person is supposed to always be in the room: to make sure Knight doesn't violate patients again. Knight's freedom to see patients without disclosing his tarnished record underscores the opaqueness of the physician discipline system across the United States, a national investigation by The Atlanta Journal-Constitution found. The AJC identified more than 2,400 doctors disciplined for sexual misconduct involving patients since 1999. Half are still licensed. No state routinely requires doctors to tell patients when they have faced disciplinary action. Four states post no disciplinary records online, and at least nine purge case files after as little as five years. Twenty-one states sometimes handle misconduct cases secretly and allow doctors to continue practice with no public hearings or public scrutiny. In 2015, advocates working with the Safe Patient Project petitioned California's medical board to require ... a doctor on probation [to] give each patient a one-page form that briefly stated his offense. At a hearing in October, board members unanimously rejected the petition.