After a deliberation of several months, the jury has reached a verdict, and found the defendant
Since there are very few legal options for white's latest moves, we can deduce that two moves ago the board must have looked exactly like this:
It is now white's turn, and the current position was reached by these moves:
1: c3 Bc2
2: b3 Nb2
(Anything else would require that the game was in an illegal position earlier, (missed possibility edited in after OP's comment:) or that the white piece that made the previous move was just captured, which would also add a ninth captured white piece to the tally.)
This means that all the bishops must have been promoted while b2 and c2 were unmoved.
Since all black pieces are accounted for, and all the 7 missing black pawns were promoted to bishops, the unmoved b2 pawn means that there can only have been one promotion on a1.
Taking this into account, let's count the minimum number of captures required to promote the black pawns:
- the black f-pawn is still on board
- the black a- and b-pawns needed two captures altogether (one capture for the b-pawn to move to the a file, and another capture for one of the pawns to promote on b1)
- the black c-pawn needed only one capture
- because both c2 and f2 were unmoved at the time, the black d and e-pawns needed to capture three pieces in total: either white's e-pawn moved before the white d-pawn, or vice versa. In either case, the corresponding black pawn needed to capture twice.
- Similarly, because of the unmoved f2, promoting the black g and h pawns required three captures.
Adding these up, we don't even need to check the colours of the bishops' squares to reach the verdict: black's promotions can only have happened if at least 9 white pieces were captured, but only 8 white pieces are missing.