A Swiss man suspected of helping to smuggle nuclear-weapons parts into Libya, Urs Tinner, has been released from prison. His brother remains in detention.
The Federal Prosecutor's Office said on Sunday that Marco Tinner was thought to possess plans for an atomic bomb. The reasons for keeping him in jail were still sound despite a federal order for him to be released.
The Tinner brothers were arrested along with their father in 2005 on suspicion of using a trafficking ring run by Abdul Qadeer Khan, the founder of Pakistan's nuclear programme, to aid Libya's atomic ambitions.
An investigation into the matter ensued and the brothers, both engineers, were held in a Swiss prison for nearly four years without being charged. Their father was released.
A few days before Christmas Urs Tinner, 43, was freed from prison, but the prosecutor filed a complaint with the Federal Criminal Court to keep Marco Tinner, 40, in custody.
The brothers have long argued that no proof of their involvement exists after the government destroyed case documents between November 2007 and February 2008.
Some believe the Tinners worked as undercover agents for the United States intelligence service and that Washington asked Bern to destroy any evidence implicating Americans in the affair.