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
It doesn't look much like a militant lair: The three-story villa's smooth, well-maintained exterior rises up behind a solid white wall in a quiet, leafy neighbourhood, wood-framed glass doors opening up on spacious balconies flanked by pillars, a BMW parked outside.
But it was inside this home that the sons of a wealthy, well-connected and now arrested pepper and cinnamon merchant, Mohammad Yusuf Ibrahim, may have planned their deadly parts in the bombings.
The developing portrait of the attackers is both maddeningly incomplete and unsettling. These men appeared to be well-educated one, for instance, reportedly studied in the UK and Australia; well-connected, with apparent links in some cases to the nation's business and political elite, and financially stable.
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
He stands in a long black robe, surrounded by other purported bombers, the only one with his face uncovered by a scarf. Clutching an assault rifle in one hand, he lifts the index finger of the other in an apparent militant salute and pledges allegiance to the IS, which distributed the video it says shows the attackers it had sponsored.
The man appears to be Mohamed Zahran, who officials said was the attackers' ringleader, and who was only recently confirmed by officials to have died in one of the suicide missions.
Zahran has been affiliated with a group called National Towheed Jamaat, which has been known for several years because of his incendiary online speeches lashing out against all non-Muslims and calling for their elimination.
THE OUTSIDE HELP
Easter Sunday again. Another CCTV camera, another man carrying a too-large backpack. This time at a luxury hotel. He enters the restaurant and pauses, awkwardly, among the tables.
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 choice of targets Christians and foreigners also suggests outside assistance. A strictly homegrown Islamic extremist attack would have likely targeted majority Buddhists because of anger over ultranationalist mob attacks on Muslims in past years.
The IS claimed quick responsibility for the attack, but only recently Australia's Prime Minister Scott Morrison announced that there was confirmation that the Lankan attackers were supported by the group.
THE SEEDS OF HATE
The Easter explosions may have seemed sudden, but experts point to a long period of gradual radicalization among some Sri Lankan Muslims.
It was only after the 2001 attacks in the US and the subsequent US invasion of Iraq, terrorism expert Rohan Gunaratna said, that radical preachers began coming to Sri Lanka, often from Saudi Arabia and Pakistan, and extremists began more regularly posting online hate.
"This type of Islam started to replace the local and traditional type, which is a very beautiful form of Islam because it accommodated other religions," he said.
Now, he said, "The floodgates have been opened.
Disclaimer: No Business Standard Journalist was involved in creation of this content
