The Journal of Jean Laffite is a document that surfaced in 1948, when a man calling himself John Andrechyne Laflin presented it to the Missouri Historical Society. At first it was believed to be genuine, but later doubts began to surface. Laflin's own past was shady, he was accused of being a forger, and people began to doubt that this was the true journal of the famous privateer whose actions in the Battle of New Orleans turned the tide in the War of 1812.
An examination of the paper and ink confirmed that they were from the 19th century and belonged to the same time period which the journal purported to have come from. The journal is not a day by day diary. It is more like the reminiscing of an older man about his past life. It is written in French and contains many newspaper clippings, rather like a scrapbook.
You would think, however, that an examination of the handwriting, and especially the signature of Jean Laffite, might be dispositive of the issue. If the manuscript was genuine, then surely the signature would match the signature in other documents from reputable sources.
As it happens, the national archives contain a letter written by Jean Laffite to President James Madison. The signature on that letter looks like this: