French authorities have taken into custody the brother-in-law of one of the gunmen who stormed the offices of French satirical magazine Charlie Hebdo in January 2015, following his extradition from Bulgaria, a judicial source told French news agency AFP.
Murad Hamid, a French national, was being sought under a Europe-wide arrest warrant and had been extradited from Bulgaria to France on Friday.
France has accused him of participating in the preparation of terrorist attacks as part of a criminal organization. The 20-year-old faces a prison sentence of up to 10 years in France.
On January 7, 2015, masked attackers killed 12 people at the magazine's offices in Paris. The gunmen, brothers Said and Cherif Kouachi, later died in a shootout with police at a hideout north-east of the French capital.
The Bulgarian state prosecution service said Hamid was apprehended while travelling by train from Serbia to Bulgaria in July, claiming that he was on "a week's holiday."