OSHA is required to protect the confidentiality of a witness in a whistleblower investigation to the fullest extent possible under the law. In fact, where witnesses wish to remain confidential in an OSHA investigation, the investigator is required at the start of the interview to say, “Your interview will be protected to the fullest extent of the law.” See US DOL Memo, Clarification of the Express Promise of Confidentiality Prior to Confidential Witness Interviews, https://www.whistleblowers.gov/memo/2016-07-15.