This is actually an interesting entire family of crimes. Steal a unique, highly valuable item, sell fake copies for full-price now that it's plausible to be the real thing (especially if you set up a sale before the actual theft takes place), then return the original if you care enough. Nobody will turn you in because they'd be admitting to attempting to buy stolen goods.
According to the article, this scheme was probably just a fabrication by a journalist who wanted a juicy story:
"Here at last was a criminal brain worthy of the Mona Lisa. The only problem is that Decker almost certainly invented him. There is no external evidence for Decker’s story, nor even for the Marques’ existence. A century later, none of the six supposed copies has surfaced. Most likely, Vincenzo Peruggia stole the Mona Lisa single-handed, largely because she was small."
(Also, this is somewhat off-topic, but the typography and layout on ft.com are really superb. This is one of the few websites that doesn't make me immediately turn to readability.)
I imagine it is a hell of a lot more dangerous now, and the guy willing to spend millions on stolen artwork is likely the guy who could have you killed without thinking about it ;-)
One of the best versions of Mona Lisa is the one engraved by Sanchez-Toda (Spanish bank note and postal stamp designer):
http://rsiqueira.postbit.com/mona-lisa
FT Weekend and FT Magazine do these sorts of stories all the time. People who spend their weekdays worrying about finance want to relax on the weekend and read fun and interesting stories.
This piece is from the FT magazine, you can see the kind of content they produce for that at http://www.ft.com/magazine
So, could perhaps be argued that the FT magazine is out of place, but within it this piece certainly fits just fine. And personally I rather like it, as an FT subscriber it's nice to get some bonus, often good, content even if it's not related to finance.
Wow that's a terrible comment - I won't even point out the difference between 100 years old and the age of humanity.
But any basic knowledge of history should tell you that anti-semitic feelings in Europe were building up in the 19th century. For example Hitler was a huge fan of Richard Wagner (who died 28 years before this 1911 theft), who wrote a famous article, first published anonymously then later republished in his own name, called "Das Judenthum in der Musik", blasting Jewish composers such as Mendlesohn.
"Art of the Steal: On the Trail of World’s Most Ingenious Thief"
http://news.ycombinator.com/item?id=1215138
"The Silver Thief"
http://news.ycombinator.com/item?id=1020547