An investigation has revealed that the Internal Revenue Service may have sent over $5 billion in refund checks to identity thieves. Those thieves, who take the identity of a deceased person or someone who would not normally file a tax return, reportedly filed fraudulent tax returns for 2011. Another $21 billion could be sent to them during the next five years. According to the Treasury Department, the IRS failed to prevent over one million potentially fraudulent tax returns from being processed last year. This resulted in refunds of over $5 billion. The investigation found a Michigan address that was used in the filing of over 2,100 tax returns for a total of over $3 million in refunds. Hundreds of refunds were also reportedly deposited to the same bank account. Tampa, FL was the city with the most tax-related identity theft, with over $468 million in potentially fraudulent refunds. Nearly $130 million of that was discovered in an identity-theft related tax refund scheme that Tampa Police said involved criminals stealing identities of the deceased.