“Joseph Cosey,” the favored alias of autograph forger Martin Coneely, comes to life in a 1956 New Yorker profile:
From the early thirties until shortly after the Second World War, [Cosey] papered the country with his handiwork—forgeries predominantly of Lincoln, but also of Franklin, Edgar Allan Poe, Mary Baker Eddy, and a score of other illustrious Americans—in such profusion that the autograph market was thrown into a state of demoralization from which it has not even yet fully recovered. …
Cosey successfully forged not only signatures but whole letters and other manuscripts in the handwriting of the signers. Ordinarily, when he attempted holographs, he reproduced an actual text verbatim, but he became so familiar with the literary style of some of the persons whose handwriting he forged that from time to time he improvised texts over forged signatures and thus ad-libbed some lines that became—temporarily, at any rate—footnotes to history.
(Hat tip: Longform)