Bradley Birkenfeld, the former UBS AG banker who won a $104 million whistle-blower award after serving time in U.S. prison for tax conspiracy, now wants to move back to Europe before his term of probation is set to end, Bloomberg News reported today. Birkenfeld asked a judge to end his probation with less than a year left or modify its terms so he can leave the U.S., according to a filing in federal court in Fort Lauderdale, Florida. Birkenfeld pleaded guilty in 2008 and was sentenced to 40 months in prison after divulging to U.S. authorities how UBS helped thousands of American clients avoid taxes.