French police said there were three suspects following the fatal attack on the Paris offices of the Charlie Hebdo satirical magazine.
Police named two as brothers Cherif and Said Kouachi, and released their photographs.
Cherif, 32, was born in the 10th arrondissement of central Paris.
Also going by the name Abu Issen, Cherif was convicted in 2008 for helping to send recruits to fight for al-Qaeda in Iraq, French news agency AFP reported.
Sentenced to three years in prison, he served 18 months before being released.
He was said to have taken up a job in a supermarket, but came to the attention of the authorities again when he was investigated for connections to convicted French islamist Djamel Beghal. No charges were brought against him.
His older brother, Said, 34, was born in the same area of Paris on Septemeber 7, 1980.
Less is known about Said, who is shown in the police photograph with short dark hair and clipped beard.
The youngest suspect is related to the brothers, French newspaper Le Monde reported.
He turned himself in to police in a town 70 kilometres from Reims where a police search was under way, but has not been charged.