The November 14 series of coordinated attacks by suicide bombers and gunmen, the deadliest inflicted on France since World War II, were a "slimmed-down version of an even more ambitious plan" to hit other European countries and following them up with strikes in several locations, a senior European counter-terrorism official told CNN.
Muhammad Usman, a suspected bombmaker for the Pakistani terror group Lashkar-e-Taiba, had set out from the capital of the self-declared ISIS caliphate in Raqqa, Syria, six weeks before the Paris attacks along with Algerian-born Adel Haddadi, the report said, citing investigation documents.
The team posed as Syrian refugees, blending in with thousands fleeing the war-torn country and made the treacherous crossing from Izmir, Turkey, into Greece in a boat filled with dozens of refugees but were intercepted by the Greek Navy.
The two who would go on to strike the Paris stadium passed through Greece - though Greek officials declined to explain how - and started moving across Europe toward their target in France while Haddadi and Usman's fake Syrian passports were discovered and they were arrested.
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They were only released in late October following which they immediately contacted their ISIS handler, Abu Ahmad, who arranged for someone to wire them 2,000 euros and the pair continued along the refugee route.
And as they travelled north, Usman was preoccupied with a strikingly un-Islamic hobby - using his phone to peruse almost two dozen X-rated sites, including "sexxx lahur" and "Pakistani Lahore college girls ... ImakeSex."
The documents - which are some 90,000 pages most of them in French and include a trove of interrogations, investigative findings and data pulled from cell phones, shedding new light on the highly organised branch of the external operations wing of the sophisticated ISIS network known as the Amn al-Kharji - also show that Usman spoke only Urdu, while Haddadi spoke mostly Arabic.