Recently, supposedly ancient letters or manuscripts by Torah
and Chassidus gedolim of several generations ago have
been offered for sale to people willing to pay enormous sums,
though the items are outright counterfeits.
These fakes are so professional that some of them were
declared authentic by an expert who did not imagine how far
the art of counterfeiting could go with the use of computers
to insert letters, words and signatures from authentic
manuscripts on old paper, thereby creating a seemingly-old
relic that is actually brand new--kankan yoshon molei
chodosh.
Marketing and distribution are done through unknowing dealers
who are convinced (or deceive themselves into thinking) that
the items are authentic and convince potential buyers
likewise.
Let it be known that besides investing money in a dubious
enterprise and the Torah prohibitions of hono'oh, gezel,
geneivas da'as, and more, when the item is eventually
sold publicly or the possessor otherwise becomes involved in
acts which are crimes, it is likely that it will be
permissible, a mitzvah and/or an obligation (which of these
three depends on the particular circumstances) to cooperate
and to reveal who sold him the item and who was involved in
the matter.
Writing to save mommon Yisroel,
Menachem Mendel HaKohen Shafran