(Reuters) — The whistleblower in a breakthrough tax fraud case against Swiss bank UBS AG has won a record-setting $104 million reward from the U.S. Internal Revenue Service, a handsome payout that could entice more informants to come forward.

Bradley Birkenfeld, who once confessed to smuggling diamonds in a toothpaste tube, was not present at the news conference on Tuesday where his award was announced by his lawyers.

He was released from prison just last month and is living in New Hampshire under home confinement at a friend's estate where he is gardening and assisting with other jobs involving manual labor on the property, the lawyers said.

Based on netting roughly $44 million after paying federal taxes and legal fees, which tax lawyers not involved in the case called a reasonable estimate, Birkenfeld realized about $46,000 for each day he spent in prison.

In a case that shook Swiss banking to its core, UBS in 2009 entered into a deferred prosecution agreement and paid $780 million in fines, penalties, interest and restitution to settle charges that it helped thousands of wealthy Americans hide billions of dollars in secret Swiss accounts.