Former banker Rudolf Elmer has been rearrested by Swiss police on new charges of breaching strict bank secrecy laws by giving data to WikiLeaks just hours after he was found guilty of similar charges in another case.
Mr Elmer (55) was taken into custody by police, having just been found guilty of breaching strict banking secrecy for publicising private client data and of threatening an employee at his former firm Julius Baer.
"The state prosecutor's office is checking to see whether Rudolf Elmer has violated Swiss banking law by handing the CD over to WikiLeaks," the Zurich cantonal (state) police and state prosecutor said in a joint statement.
At a news conference in London on Monday, Mr Elmer handed over data on hundreds of offshore bank account holders to WikiLeaks founder Julian Assange, saying he wanted to draw attention to financial abuses.
WikiLeaks has angered US authorities by publishing hundreds of secret diplomatic cables.
Mr Elmer, who helped bring WikiLeaks to prominence three years ago when he used it to publish secret client details, had admitted sending Julius Baer data to tax authorities. But he had denied blackmail and a bomb threat against Julius Baer and said he never took payments in return for secret data.
The banker spent a month in investigative custody in 2005 when the charges were first made against him.
"I am a critic of the system and want to tell society what happens in these murky oases," Elmer, who ran the Cayman Islands branch of the Swiss bank dedicated to wealthy clients until he was fired in 2002, told a news conference before the verdict.
Julius Baer, which has denied its Cayman branch was used for tax evasion, claimed Mr Elmer waged a "campaign of personal intimidation and vendetta" against the bank after it refused his demands for financial compensation following his 2002 dismissal.
Protesters from the left-wing Alternative Liste party had gathered outside the court, holding up a banner, saying: "They want to hang Rudi, they let Kaspar off the hook", in a reference to UBS chairman Kaspar Villiger.
Switzerland last year gave details of about 4,450 UBS accounts to US authorities as part of a deal to settle a tax probe into its biggest bank despite strict secrecy laws. None of its bankers were prosecuted in Switzerland.
Mr Elmer, a certified auditor who also worked at Credit Suisse and KPMG, had argued Swiss bank secrecy should not apply, since the documents he leaked referred to accounts in Cayman.
Swiss bank secrecy has come under global attack in recent years, with neighbouring Germany buying secret data from informants in a bid to track down tax evaders.
