A 32-year old man working at the Centre for Nuclear Research (CERN) is facing terrorism charges in France following his arrest last week.
The man was arrested along with his brother last week in Viene, south-east France. His brother has been released.
The physicist is facing charges of "criminal association with a terrorist enterprise." He was in email contact with Al-qaeda groups in north Africa, according to the BBC.
But under French law being charged with an offence does not automatically lead to a trial. The investigating magistrate will continue to probe before deciding if charges should be answered in court or dropped.
CERN issued a statement making clear the non-scary nature of most of the material it uses and that the arrested man actually worked for a subsidiary lab.
Our field of research is particle physics and addresses fundamental questions about the nature of matter and the Universe. In the course of our research, we use the kind of radioactive sources that are commonly found in hospitals and in industry, and we apply standard security procedures to their handling. CERN does not possess materials that could be used for terrorism.
CERN said the man arrested was an employee of one of its user institutes which is a member of the large hadron collider experiment.
The lab said that much of its site "consists of office space, and resembles any University campus." It will continue to assist police with their investigation.
The hadron collider runs underground between French and Swiss territory. Early experiments were cut short by a dodgy cable in July.
It hopes to restart its search for Higgs boson particles in November. ®