Eight of the nine bombers that killed 359 people in Sri Lanka have been identified.
According to BBC all are believed to have been home-grown, one was a woman and most came from “middle or upper middle class” families,
Two of the bombers were the sons of a wealthy and well-known spice trader, Mohammad Yusuf Ibrahim, who is based in the Sri Lankan capital, Colombo, police sources have told the BBC.
Their father has been arrested and is now in custody.
His daughter-in-law detonated explosives during a police raid at the family’s villa on Sunday, apparently to avoid arrest.
Several people, including children and police officers, were reportedly killed in that blast.
The family’s wealthy background matches the description of the attackers given by the authorities.
“They are financially quite independent and their families are quite stable financially,” Deputy Defence Minister Ruwan Wijewardene said at a press conference on Wednesday.
One of the attackers studied in the UK, Identified as Abdul Latif Jamil Mohammed who visited south-east England in 2006-7 to study but did not complete a full university degree, a senior Whitehall official told the BBC.
He reportedly studied aerospace engineering at Kingston University.
Islamist preacher Zahran Hashim is suspected of being the bombers’ ringleader. Police do not know whether he detonated one of the suicide bombs or is still at large.
An IS video that was released after the group said it had carried out the attacks appears to feature him prominently.
In the video, he can reportedly be seen pledging allegiance to the group’s leader, Abu Bakr al-Baghdadi.
Sri Lanka’s Muslim community have said they warned the authorities about Mr Hashim for years prior to the attacks.
“This person was a loner and he had radicalised young people,” Hilmy Ahamed, vice-president of the Muslim Council of Sri Lanka, told AFP news agency,
“Nobody thought these people were capable of carrying out an attack of such magnitude,” he added.
Mr Hashim’s sister told the BBC: “I came to know about his actions only through the media. Even for a moment, I never thought that he would do such a thing.
“I strongly deplore what he has done. Even if he is my brother, I cannot accept this. I’m not worried about him anymore.”