Which preposition to use with unaccounted

for Occurrences 18%

It is only to talk in general terms of places and pensionsthe loaves and the fishesa struggle for powera struggle for powerAnd it will do excellent well, if at a critical momentyou can throw in a hint of some forty or fifty millions unaccounted for by some people's grandfathers and uncles dead fifty years ago.

Which preposition to use with  unaccounted