Much of the coverage of Wednesday’s Charlie Hebdo massacre has framed the murder of 12 people at the magazine’s Paris office as an assault on freedom of expression. But a closer look at the biography of a key suspect who remains at large suggests political motivations that run deeper than rage at cartoons insulting the Prophet Muhammad.

University of Michigan Middle East scholar Juan Cole told Al Jazeera that Cherif and Said Kouachi had been “radicalized by the war in Iraq, long before the cartoon issue ever erupted.” And in a worldview honed a decade ago by rage over the U.S.-led invasion of Iraq, the Charlie Hebdo cartoons were taken as affirmation of a notion that Western powers were waging war on Muslims.

The Kouachi brothers were certainly no strangers to French security services when their images flashed around the country on wanted notices — if anything, they'd have been among the proverbial "usual suspects." The younger brother Cherif, also known as Abu Issen, had been arrested in 2005 while en route to join the fight against the U.S. and its allies in Iraq, and he later spent time in prison as a result, France24 reported. The names of both brothers had been on the U.S. "no-fly" list, and CNN is now reporting that U.S. officials have been told by French counterparts that the older brother, Said, had received military training from Al-Qaeda in Yemen.

Details of the Kouachis’ background published in French and international media paint a picture of a path to violence that predates Charlie Hebdo’s first publication, in 2006, of cartoons that ignited controversy in part of the Muslim world.

The orphaned brothers had been born in Paris to immigrant Algerian parents, and had grown up poor and often unemployed — in a milieu of young French citizens of Arab origin seething with resentment at their social marginalization (an anger that exploded in nationwide riots in late 2005).

Cherif Kouachi reportedly became enraged by the U.S. invasion and occupation of Iraq in 2003 and in particular by photographs that first began leaking to the media in 2004 depicting U.S. soldiers abusing and humiliating Iraqi detainees at Baghdad’s Abu Ghraib detention center. Le Monde reports that at a local mosque, Cherif came under the influence of Farid Benyettou, who preached about the virtues of violent jihad in Iraq and advocated suicide bombing as a legitimate tactic.

Benyettou was accused of being part of an underground group known as the “19th District,” which had sent about a dozen young men from France to fight in the ranks of Al-Qaeda in Iraq.

Cherif was arrested in 2005 for attempting to travel to Damascus, from where he was supposed to find his way to Iraq to join the fight. In 2008, Cherif was convicted and sentenced to three years in prison, 18 months of which was suspended, for conspiracy to prepare acts of terrorism. The older brother, Said, was taken in for questioning at the time but eventually released without being charged.

While in prison, Cherif is reported to have been mentored by Djamel Beghal, a Frenchman of Algerian heritage who had been convicted in 2005 for plotting a 2001 on the attack the U.S. embassy in Paris.

Cherif was arrested again in 2010 for allegedly attempting a prison-break to free Smain Ait Ali Belkacem, who is serving a life sentence for involvement in the Algerian Armed Islamic Group (GIA) 1990s bombing campaign on Paris railways. Cherif was released months later without being charged.

It is unknown if Cherif was ever able to leave France and return without detection. U.S. and European sources have reportedly said the older brother Said had traveled to Yemen and trained with Al-Qaeda in the Arabian Peninsula (AQAP) for several months. Other unconfirmed reports say the brothers had visited Syria in 2011. Wednesday's "operation made some mistakes but it was not amateurish," Cole said. The calm and professional manner in which Wednesday’s attack had been executed led many security analysts to conclude the perpetrators had undergone some form of training and had undertaken considerable planning.

In recent years, more citizens of France than of any other European country have reached Syria and Iraq to fight in the ranks of the Islamic State movement or the Al-Qaeda-linked Jabhat Al-Nusra.

Juan Cole says attacks such as the one on the Charlie Hebdo offices fit an Al-Qaeda strategy to amplify the movement’s appeal to angry and marginalized young Muslim men. Al-Qaeda is “actually a fringe group,” said Cole, but “when they do something dramatic like this, it makes them look important.”

Crucial to the effect of such actions is the response they prompt. “Backlash is good for them because they want to recruit Muslims,” Cole said, explaining that creating divisions between Muslims and the wider French society potentially increases the recruitment pool for radical groups.

Many details of the Paris massacre remain hazy, of course. But if Cherif Kouachi turns out to be one of the perpetrators, as French police suggest, then his history suggests the attack was far more than an impulsive act of terror spurred by a habitually provocative magazine.