Like the Boston bombing in 2013, the Charlie Hebdo massacre has come to a tale of two brothers. The chief suspects, Cherif (32) and Said Kouachi (34), were said to be on the run last night in countryside 80 miles north-east of Paris.
The brothers are French. They were born to Algerian-born parents in Paris, a few blocks from the scene of Wednesday's savage attack. As small boys were brought up in a children's home in Brittany.
Cherif, especially, was well-known to French security. He has served two periods in prison after being linked to an Islamist network which sent fighters to Iraq from 2003-6.
Despite reports to the contrary, he does not appear to have fought, or received training, abroad. Although still under surveillance, he was regarded by French internal security as a low risk "has-been".
Awkward questions will inevitably be asked about the failure of anti-terrorist agencies to spot the brothers as a serious threat. The explanation seems to be that Cherif was regarded as "too old" - a failed wannabe jihadi who had reverted to the chaotic existence of his early 20s. Said, though older, had always been in Cherif's shadow. He had never been seen as any sort of threat.
All French security's efforts have been focused in recent months - with some success - on preventing domestic acts of terror by jihadis returning from Iraq and Syria. These men are often recent recruits to the cause and, in some cases, recent converts. Cherif, and therefore Said, were overlooked as they belonged to a previous generation.
Cherif, according to Vincent Ollivier, his former lawyer, went into his first prison term in 2006 as a confused kid and emerged as a physically stronger radical. One of the Islamists with whom he consorted in jail was Salim Benghalem, now regarded by the US as a principal organiser of Isis in Syria. French officials believe Wednesday's was likely a freelance attack, inspired by Isis, but not directly ordered or controlled from the Middle East.
The Kouachis do not have the typical profile of converts to radical Islam. Aged four and two, they were placed in a children's home in Rennes before being fostered by a family who had converted to Islam.
Cherif qualified as a sports teacher and worked in Rennes - a 2005 Facebook post shows him rapping. The brothers moved to Paris where they became involved in petty theft and drug dealing.
Cherif was first radicalised, said Ollivier, by the US-led invasion of Iraq. He was convicted in 2006 of aiding and abetting a terrorist organisation and sentenced to 18 months in prison - a term which he had already served on remand.
In 2010, he was arrested and served another six months on remand on suspicion of belonging to a jihadi group trying to spring a leader from jail. He was rereleased without trial after persuading investigators he had joined the group only to "play football".
Cherif then dropped off the security services' radar. Said scarcely merited a blip on their screens.
Sixty seconds of solidarité. A minute of silence is the small but poignant gesture that took place in newsrooms and workplaces worldwide yesterday to mourn the loss of 12 people following the massacre at Charlie Hebdo offices in Paris on Wednesday.