[Icare9]

Hi and welcome squawk.
Presumably you have some additional information to suggest lakes around Berlin as a possible crash site?
Most aircraft and crew that remain as Missing have to be inferred as crashing into the North Sea, rather than into a fairly small or shallow lake, where by now, most have been searched and anything potentially associated with a WW2 bomber recovered, if only to ensure no nasty munitions left to go "bang" unexpectedly.
2 of the crew were RAAF, so there is a strong possibility that additional information may exist in the Australian Service files, which I believe can be released upon application and payment of a fairly small fee. (No doubt other more expert Pals will advise the proper course of action, if you don't find it by "Search"!) especially as one was a PoW.
Did he complete a debriefing on how and where he believed they were shot down?
If there are details as to where he was first held, what camps he went to, then it may be possible to at the very least rule out the North Sea (if they baled out well inland, could the aircraft have reached the coast?).
Most wreckage that fell in Occupied Territories would have had "helpful" locals to report its location, once they were liberated.
it may simply be that the aircraft was destroyed by a mid air explosion, crashed detonating its bomb load with little wreckage remaining or simply crashed into the target area and destroyed by subsequent bombs.
Hope that helps...