Cherif, who was born on November 28th, 1982 in Paris not far from where the attack took place, had already been jailed in 2008 for his role in sending fighters to Iraq.
Sometimes going by the name Abu Issen, he was part of the "Buttes-Chaumont network" led by Farid Benyettou, that helped send would-be jihadists to join Al Qaeda in Iraq during the US-led invasion in the mid-2000s.
He was arrested just before he was due to fly to Syria and on to Iraq — and was later sentenced to three years in prison, including an 18-month suspended sentence.
Two years later, his name was cited in a police report related to the attempted prison escape of Smain Ait Ali Belkacem, a former member of the Algerian Armed Islamic Group (GIA) that carried out a spate of bombings and a plane hijacking in France in the 1990s.
Belkacem was sentenced to life imprisonment in 2002 for a bombing at the Musee D'Orsay rail station in Paris in October 1995 that left 30 injured.
Cherif Kouachi was also suspected of being close to another key French jihadist, Djamel Beghal, who spent 10 years in prison for planning attacks.
They were suspected of participating in militant training programmes together, although charges in this case were dropped against Kouachi.
Armed and dangerous
With a shaved head and sparse goatee in the photo sent out by police, Cherif Kouachi is considered "armed and dangerous".
His brother Said was born on September 7th, 1980, also in Paris. His photo shows him with brown eyes, lightly bearded with short brown hair.
Their presumed accomplice, who handed himself into police in northeastern France was identified as Mourad Hamyd, the 18-year-old step-brother of Cherif Kouachi.
He is suspected of helping the two brothers in the attack, with one witness saying a third man was in the car when they made their getaway.
Hamyd presented himself to police in the town of Charleville-Mezieres "after seeing his name on social networks", a source close to the investigation told AFP.
Several of his school friends had taken to Twitter saying he had been in class with them at the time of the attack, using the hashtag #MouradHamydInnocent.