Investigate the Investigators Act of 2019 This bill requires the Office of the Inspector General (OIG) for the Department of Justice (DOJ) to conduct oversight of investigations of certain political officials. In the case that the President, the Vice President, a Senator, a Member of Congress, or a candidate for any such office or the campaign of such candidate is a subject of an investigation conducted by DOJ, DOJ shall provide to the DOJ OIG a notice of such investigation by five days after such investigation commences. The bill directs the DOJ OIG to commence an oversight investigation to ensure that, among other things, the decision to investigate the conduct of the official was not influenced by political pressures or politically motivated objectives and that evidence used in the investigation is obtained by lawful means and not tainted by political sources or motives. Upon opening such investigation, the DOJ OIG shall notify specified officials that an oversight investigation subject to this bill has commenced and that a report will be issued at the conclusion of the investigation, with exceptions. Not later than 90 days after the conclusion of the investigation, the DOJ OIG shall submit to DOJ and specified officials a report on its findings. During the investigation, if DOJ fails within 30 days to remedy a serious or flagrant issue raised by the OIG, the OIG shall make an immediate report to such officials.