Justice Department investigating Interior Secretary Ryan Zinke. So THAT'S Why they tried to replace the Inspector General.

https://www.cnn.com/2018/10/30/politics/zinke-justice-department/index.html
The Justice Department is investigating Interior Secretary Ryan Zinke for possibly using his office for personal gain, following a referral from Interior's inspector general, two sources familiar with the investigation say.

https://www.reuters.com/article/us-usa-interior-zinke/probe-into-conduct-of-u-s-interior-secretary-zinke-referred-to-doj-reports-idUSKCN1N42IV

Referring a probe to the Justice Department means it will explore whether evidence warrants a criminal investigation. Mary Kendall, the acting inspector general of the Interior Department, is conducting at least three probes into Zinke’s conduct, but it was not clear which probe had been sent to the Justice Department, the Washington Post said.

https://thehill.com/policy/energy-environment/411631-hud-political-appointee-to-replace-interior-department-inspector

HUD political appointee to replace Interior Department inspector general

https://www.nbcnews.com/politics/white-house/amid-confusion-interior-department-says-hud-official-not-taking-over-n921876 

Instead of becoming Interior Department inspector general, Tufts resigns from HUD

Questions were raised after a report that a Trump political appointee was about to replace the watchdog investigating Interior Secretary Ryan Zinke.