“Bitcoin heists are actually not uncommon. In June of 2011, a user named Allinvain was the victim of what is arguably the first recorded major Bitcoin theft. There have been dozens of Bitcoin thefts since then. The supposedly high-return investment fund Bitcoin Savings & Trust turned out to be a pyramid scheme, its owner charged with ripping off investors for $4.5 million in bitcoins. MyBitcoin, a ‘wallet’ service that stored bitcoins like a bank account, disappeared with about $1 million worth of users’ bitcoins. Several of the most trusted and well-known Bitcoin companies, including the Mt. Gox and the now-defunct Bitcoinica exchanges, have also suffered high-profile thefts.”
http://www.theverge.com/2013/12/19/5183356/how-to-steal-bitcoin-in-three-easy-steps