A French physicist at a Swiss laboratory that houses a giant particle accelerator, has been charged with membership of a terrorist group.
His brother was also arrested but later released.
Officials said he had been in contact with people linked to al-Qaeda in the Islamic Maghreb and planned attacks.
The BBC reports he had been working on an experiment at the Cern laboratory which houses the Large Hadron Collider, designed to recreate the conditions that existed just after the Big Bang. It is located on the Swiss-French border.
On Monday, a laboratory spokesman said the man had not been seen at work for most of the year because he was ill, but that he had been in touch via e-mail.
The scientist, 32, has appeared at a court in Paris to face charges of "criminal association with a terrorist enterprise".
The BBC reports he was placed under formal judicial investigation. His brother, 25, was released without charge.