From 1942 to 1945 the german atomic program was an experimental low-funding program destined to investigate the possible use of reactors as power sources and, possibly, their viability to build an atomic bomb...in 5 or 6 years in the future (we're speaking about 1945 here). Thats why the german scientifics were absolutely stunned by the fact that the US already had a working A-bomb after Hiroshima.
There is a lot of literature about the German atomic program. Some of said literature seems to paint a view of a germany really nearing the completion of one or more atomic devices already by 1944. All of it speaks about covert investigation groups working out of the main atomic program, headed by Heisemberg.
None of them hold any truth. Not only all those books are -without exception- written by revisionists, there were no hidden atomic research groups in germany, it was impossible for Germany to hide a program of this scope. The ammount of funds, scientist, technicians, matherials, etc, needed for such an undertaking was impossible to hide.