One of brothers hunted over the attack on the satirical magazine Charlie Hebdo is reported to be a committed Islamist who was well-known to police.
Cherif Kouachi, 32, was first considered to be a possible terrorist by the French authorities when he was in his early 20s.
He was believed to have come under the influence of a radical Paris-based Islamic preacher and became more radical himself following the US invasion of Iraq.
The younger of two brothers, Cherif Kouachi was arrested in 2005 just before he was due to travel to Syria and on to Iraq.
He was later sentenced to three years in prison, including an 18-month suspended sentence.
Kouachi, originally from the Paris suburb of Pantin,was also reportedly convicted of a criminal charge in 2008 after associating with an illegal organisation backing jihad in Iraq.
According to the lawyer who represented him at the time of his 2005 arrest, his client was not always a committed Islamist.
"He smoked, he drank, he didn't have a beard and had a girlfriend before marriage," Vincent Ollivier said.
Said Kouachi, is also being sought in connection with yesterday's shootings.
According to Le Figaro the older brother is married, lives in Reims and is said to have got on well with his neighbours.
Cherif Kouachi was reportedly raised in foster care in Brittany after the two brothers became orphaned as children when their Algerian-immigrant parents died.