Stealing valuable works of art is one of the biggest criminal trades in the world today, just behind drug trafficking, arms dealing, and money laundering. According to Interpol, tens of thousands of artworks are stolen every year, with worldwide losses of up to $6 billion.

Art theft has had a high profile in the public view since the early 20th century. In 1911, Vincenzo Peruggia stole the Mona Lisa from the Louvre, which took two years to recover. The Germans in World War II were infamous for plundering thousands of artworks during their occupation of countries like Poland and France. Some of these artworks are still being rediscovered and reclaimed, such as the discovery of a secret Munich collection of 1,500 artworks in 2012.

The most infamous case of recent art theft occurred in 1990, when two thieves managed to steal 13 art pieces--collectively worth $300 million--from the Isabella Stewart Gardner Museum in Boston. At the time of this writing, they have yet to be recovered.

For some art thieves, the pleasure in secretly possessing a valuable work of art is reason enough to commit the crime. Others might use the art as collateral to secure loans or to fund other criminal activities, including terrorism and money laundering. This can also be achieved if the work comes from a private collection and is being held for ransom. In general, art thieves find their work to well worth the effort, as most art pieces are usually light enough to carry and can be sold for thousands, if not millions, of dollars.

Museums and art collectors have taken many steps to preventing their art from being stolen, usually with varying degrees of success. The most common tactic is to increase surveillance, whether through security cameras and electronic alarms or by keeping enough docents and guards available to watch the items on display. Another strategy is to fasten the artwork in place using hanging wires and locks. Most art owners also decide to take out insurance on the items in their collection, whether on display or in storage.

Sadly, just as there are always new ways to steal art, there are few chances of successfully recovering what was stolen. Some thieves will simply fence the work to a new buyer without ever informing them that the work was stolen, making it difficult to prove theft against a "bona fide" claim. However, most security experts recommend that the owners register their works early on, so that groups like the Art Loss Register can scan for and detect stolen art pieces at auctions and galleries.

For more information and resources about art theft, you can consult with the Art Loss Register, the FBI Art Crime Team, the Art and Antiques Unit in New Scotland Yard, and Interpol.

Image by Christopher Macsurak on Flickr