What happened to Gestapo Chief Heinrich Muller?

He began to "self identify" as a female and called himself Hillary Rodham.

He was seen in Argentina and Paraguay

"Gestapo" Mueller's ultimate fate is one of the many unanswered questions surrounding the fall of Berlin.  I actually read the file on him at the National Archives in College Park, MD -- the Hoyer Annex. There is one interesting note:  Around 1960, his wife received a packet containing several of his medals when the area around ss HQ excavated to put in sewer pipes.  Here is what probably happened.  During April 28, he interrogated Hermann Fegelein to determine the extent of what was called the Himmler Treason.  Fegelein's briefcase was found to contain a number of incriminating documents.  After Mueller turned Fegelein over to the courts martial which ordered his execution, Mueller made his was out of the bunker to ss HQ where a last stand was being planned.  He died in the attack, and was hastily buried in a makeshift grave among the rubble of the building along with the other 'last standers' of ss HQ.  Anyway, that is my guess, and my colleagues suggest that this end for him is about 65 per cent probable. 

I typed your q in Google search. The answer is there. Why would you think we're privy to something different?

 The whereabouts of Müller has ever been found and he remains the highest-ranking member of the Nazi regime whose fate remains a mystery.

He opened up a greengrocery in Munich, kept pigeons and became an advocate of the health benefits of aubergines.

He renounced being a Nazi after the war and set up in the yoghurt making business. His yoghurts have a fruity bit in the corner.

Much Like Hitler Body never Found

Heinrich Müller, whose date of death is unknown but suggested to be May 1945, was  the chief of the Gestapo and central to the planning and execution of the Holocaust.  He was last seen in the Führerbunker in Berlin on 1 May 1945 and remains the most senior figure of the Nazi regime who was never captured or confirmed to have died.