A number of witnesses survived to testify and provide a reasonably compelling narrative that points to the suicide of Hitler and Eva Braun, followed by the cremation of their corpses. The remains were disposed of outside the Chancellery, where they were intermingled with numerous other corpses, which is important. The Russians searched very hard to find the remains of Hitler, and eventually recovered several pieces they believed belonged to him. The key identification at the time was the piece of jawbone and dental bridge that were recovered and were conclusively identified using his dental records. While recent testing has shown that the piece of skull fragment that often was mentioned as being his did not actually belong to Hitler (it was female), they were never certain about that in the first place and the association was based off a bullet hole rather than anything else. It was not recovered with the jawbone, but rather, it was only found a year later, in 1946. It played no part in the initial identification.

The oft-brought up thing about the FBI report supporting the idea Hitler survived, has no basis. The report in question was a compilation of various supposed sightings, but they are mostly contradictory and stretch would stretch the credulity of even the most gullible of people. It is mostly composed of what one might call "a crank file".

See Kershaw's "Hitler: Nemesis 1936-1945" for a slightly more in-depth focus on this.