Death came to Sri Lanka in rucksacks worn by eight men.

The suicide bombers struck churches and hotels within minutes of each other, turning the innocence of Easter Sunday into scenes of terror.

Two days later Islamic State said it carried out the bombings, releasing a video of suspects pledging allegiance to its leader Abu Bakr al-Baghdadi.

Only one face is unmasked. That of Mohammed Hashim Mohammed Zaharan, in his early 30s, a self-styled radical preacher and the suspected ringleader of the group.

He targeted the Shangri-La hotel in Colombo with another bomber.

The other seven men - a woman is also suspected of blowing herself up after the initial assault - who took part in the carnage on 21 April are from different parts of Sri Lanka.

They are largely well-educated, well-travelled and with wealthy families

CCTV images of the bombers from that day illustrate their coordination and training.

They used identical rucksacks to carry their explosives. Most were pictured with baseball caps to hide their faces.

Two were caught on camera in a change of clothes to conceal their tracks.

Some were seen on their mobile phones, possibly receiving instructions from someone else, perhaps evidence of a wider network.

Security sources in Sri Lanka warn that more bombings could happen because other members of the group remain on the run despite a massive operation to round up suspects.

Seven hours' drive from Colombo is the majority Muslim town of Kattankudy on Sri Lanka's eastern coast.

This is where Zaharan was born into a poor family, the eldest of five children.

Friends described him as an arrogant but compelling orator, with hard-line views on Islam.

But leaders of the Muslim community were damning, saying he was expelled from a religious college for breaking rules and excluded from a mosque for lying.

He set up his own group: National Towheed Jamaat, or NTJ in 2012, using it as a platform to criticise others, even those of his own faith who didn't agree with him.

But after five years members of his own organisation had grown tired of his radical stance, writing to him to say he had been expelled.

Mohammed Yusef Mohammed Towfeek, who has known Zaharan since 2002, took over as leader of the NTJ.

He claimed Zaharan only showed he was an IS supporter through online posts after he fled the town in 2017, wanted by the police for fighting with another group.

"When he was talking over the Internet he was saying: this parliament is not good, the law is not good, different Muslim groups are not good," Mohammed Towfeek said.

Asked how he felt about his long-time friend being the ringleader of the Easter bombers, he replied: "I feel angry and I feel ashamed because Zaharan betrayed me. We'd spent so much time together and we started the NTJ together - but he has betrayed me."

A couple of hours later, Mohammed Thowfeek was arrested by police in a raid on the mosque.

Officials have linked the NTJ and another little-known Islamist group to the attacks.

He denied the claim, saying his organisation had cut ties with Zaharan and his followers.

Often found ranting online, Zaharan was on the radar of Indian intelligence for his radical views but wasn't hunted down by Sri Lanka despite warnings from India about a possible attack in the making.

Instead he was able to transform into a suicide bomber, resurfacing at the Shang-ri La hotel to kill.

A second bomber, Abdul Latief Jameel Mohammed, 36, studied engineering in the UK for a year and a half from 2006. He also did a post graduate in Australia.

His mission on the day of the attacks did not go to plan.

He is pictured in a photograph looking at his phone as he posed as a guest at the five-star Taj Samudra hotel in Colombo.

Sky News understands he positioned himself at a table - most likely in a breakfast dining area - and tried to detonate the bomb on his back.

Three times he attempted to activate the charge but it didn't work.

A source said CCTV footage shows that his mobile phone, on the table behind him, then suddenly rang - a further suggestion of external elements being involved, possibly calling him to find out why there had not yet been a blast at the hotel.

He is then pictured kicking the table in frustration before leaving the hotel, switching into a different shirt and retreating to the outskirts of the city.

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