Two brothers are suddenly the most wanted men in France, suspected of the armed onslaught on a newspaper office that claimed a dozen lives and horrified this country and much of the world.

Cherif Kouachi, 32, and Said Kouachi, 34, became the targets of a mammoth manhunt following Wednesday's murderous attack at the Charlie Hebdo offices in Paris.

The younger Kouachi had been sentenced to 18 months of prison in 2008 after trying to leave to join Muslim fighters battling in Iraq.

Associated Press reporters who covered the trial, which exposed a recruiting pipeline for Islamic holy war in a rough multiethnic and working-class neighborhood of northeastern Paris, recalled a skinny young defendant who appeared very nervous in court.

Cherif Kouachi's lawyer said at the time his client had gotten in with the wrong crowd, and in over his head.

During the trial, Kouachi was said to have undergone only minimal training for combat, going jogging to shape up physically and learning how a Kalashnikov automatic rifle works by studying a sketch. The former pizza deliveryman was described as a reluctant holy warrior, relieved to have been stopped by French counterespionage officials from taking a Syria-bound flight that was ultimately supposed to lead him to the battlefields of Iraq.

But imprisonment changed his former client, attorney Vincent Ollivier told Le Parisien newspaper in a story published Thursday. Cherif Kouachi became closed off and unresponsive, and started growing a beard, Ollivier said. The time in prison, the lawyer said, may have turned him into a time bomb.

Less is known publicly about the older Kouachi, but Prime Minister Manuel Valls told French radio Thursday that both brothers were known to intelligence services and were likely being followed before the Charlie Hebdo attack.

A third suspect identified by French authorities in the assault, in which 12 people were injured, has turned himself in.