Brandon Lee Price, 30, of Pittsburgh, pleaded guilty to four counts of bank fraud and must return for sentencing Sept. 30.
Most of the transactions Price attempted did not go through, as they were flagged as suspicious by Citibank, which issued the card. But Price was able to pay $658.81 toward a delinquent Armed Forces Bank loan in Fort Leavenworth, Kan., in January 2012, Assistant U.S. Attorney James Wilson said.
"This case with this high-profile victims calls attention to the seriousness of the crime of identity theft," U.S. Attorney David Hickton said.
Microsoft and Citibank did not immediately respond to requests for comment Thursday.
Price had left his unit without permission at Fort Polk, La., in July 2010 and wasn't found until the FBI arrested him in Pittsburgh in March 2012. Fort Polk officials did not immediately return a call, but Wilson said after Thursday's hearing that Price has since been court-martialed and discharged.
In order for Price to plead guilty, Wilson had to detail the evidence for the judge, explaining the scam began when Price called Citibank in late December 2011 and pretended to be Allen.
Price told a customer service representative "he was attempting to do online banking and needed his debit card number" but didn't have it handy, Wilson said.
Price was able to give the rep the last four digits of Allen's Social Security number, the last two digits of a debit card account and the entire number for one of Allen's checking accounts, Wilson said. Despite that, Citibank didn't give Price the account number he sought, though he did get the number two days later when he called Citibank back and provided additional personal information about Allen.
Price then changed the address on Allen's account to Price's home address in Pittsburgh, and after again pretending to be Allen and claiming the card was lost, Citibank sent a replacement to Price's home.
Price first used the card to make the delinquent loan payment, then attempted several transactions that didn't go through, including a $1 purchase at a dollar store near his home.
Price also tried to use the card to make three transfers - of $94,000, $800,000 and $130,000 - to accounts he controlled. He also unsuccessfully tried to open an investment account with a $388,000 funds transfer and to purchase $250,000 in certificates of deposit, Wilson said.
FBI agents later determined Price logged onto publicly available computers at a local job center, where he searched for topics including "identity theft," ''brokerage accounts" and "Paul G. Allen." Wilson said he doesn't know why the billionaire was targeted.
Wilson called it a "very odd case" given that Price appears to be a "very marginal person who drifted through the Army and appears to be pretty inept at almost every aspect of daily normal life."
Both Price and his federal public defender declined to comment.
Bank fraud carries a sentence of up to 30 years in prison, but Price's case will be governed by guidelines dictated by the amount stolen. The government argues the "loss" is the $1.6 million Price tried to steal, but his attorney contends it's merely the $658.81 he actually siphoned from Allen's account.