An impatient little girl in a pretty dress pulls on the hand of a man, possibly her grandfather, as they cross a brick courtyard outside St Sebastian's Church on Easter Sunday.
Directly in her path a slightly built, bearded man, bent beneath the weight of a large backpack, slows down so he doesn't bump into the girl, his fingers seeming to touch her hair for just an instant as she passes.
And then, CCTV cameras show, they both go about their day a common, almost mundane interaction made chilling only by what happens next.
The man walks into the church packed with worshippers, a ceiling fan whirring above, and, according to authorities, detonates the bomb in his bag, part of a coordinated set of attacks on churches and luxury hotels across the country that killed more than 250 people.
Officials are now hunting for clues that might explain how a little-known Islamic radical group went from defacing Buddhist statues and posting online screeds to pulling off one of the most stunning and brutal attacks in recent years.
From a copper factory outside Colombo where the bombs may have been put together, to a respected spice merchant's luxury compound in the capital where his two wealthy, radicalized sons reportedly planned their parts in the bombings, to a hothead mastermind who seems to have sharpened his building hatred with help from the IS a picture of a determined local militant cell that suddenly went global is slowly emerging from the immediate aftermath of grief and confusion.
As the bombers' motivations and backgrounds come into focus, Sri Lanka, which dealt with homegrown terror of a much different sort during a nearly three-decade civil war, is struggling to understand how a sliver of local Muslims broke off from what had been a relatively inclusive form of the religion for years and apparently joined an international militant network whose brand is mass murder on a spectacular scale.
THE SPICE BROTHERS
So how could some of Sri Lanka's most well-off citizens fall prey to virulent extremism? Prime Minister Ranil Wickremesinghe offered this not altogether satisfying explanation: "They were too educated and, therefore, they were misled."
THE MASTERMIND
THE OUTSIDE HELP
The world has zeroed in on what officials say happens next the carnage and the misery but police have been trying to answer another very specific mystery: How did this tiny, little-known Sri Lankan group suddenly orchestrate a large-scale, nearly simultaneous suicide bombing attack against busy churches and hotels across the country?
THE SEEDS OF HATE
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