The sister of the British-educated Sri Lanka suicide bomber has revealed how he became radicalised abroad and ended up 'really angry and totally crazy' – even telling off male relatives for trimming their beards.

In an exclusive interview Samsul Hidaya said Abdul Lathief Jameel Mohamed had been educated to the highest level but became increasingly withdrawn and intense as he descended into extremism.

'My brother became deeply, deeply religious while he was in Australia,' she said. 'He was normal when he went to study in Britain, and normal when he came back.

'But after he did his postgraduate in Australia, he came back to Sri Lanka a different man.

The sister of British-educated Sri Lanka suicide bomber Abdul Lathief Jameel Mohamed (pictured as a school boy) has revealed how he became radicalised abroad and ended up 'really angry and totally crazy' – even telling off male relatives off for trimming their beards

Mohamed's sister opened the family photo album to show childhood pictures of the future bomber show the practical joker as a teenager, laughing with friends as he posed with a crocodile and other animals before he became radicalised

In an exclusive interview, Mohamed's sister said had been educated to the highest level but became increasingly withdrawn and intense as he descended into extremism

Mohamed, one of six siblings, was from a wealthy tea trading family based near the central city of Kandy. He lived in this house in an upmarket part of Colombo which was raided on Monday

Mohamed's sister said her sibling lost a lot of his childhood innocence, becoming serious and withdrawn - adding 'He would not even smile at anyone he didn't know, let alone laugh.'

'He had a long beard and had lost his sense of humour. He became serious and withdrawn and would not even smile at anyone he didn't know, let alone laugh.'

Mohamed tried to blow up the luxury Taj Samudra hotel in the Sri Lankan capital Colombo on Easter Sunday.

But he is believed to have botched his attempt to detonate his bomb at the five-star hotel and is thought to have blown himself up by accident at a much smaller guest house.

UK counter-terrorism investigators believe he attended Kingston University in south-west London from 2006-07.

British investigators are searching for any associates or signs of extremist activity during his time in the UK.

Recalling the shock of his involvement in the atrocity which claimed 359 lives, Mrs Hidaya opened the family photo album to show childhood pictures of the future bomber show the practical joker as a teenager, laughing with friends as he posed with a crocodile and other animals.

'He was a music lover and a funny boy,' his sister said. 'It makes me sad to think what happened to him. Before he died he would not let his children listen to music and he never said a friendly word to anyone.'

Even as a child he was always devout, she added, but had 'never taken it too far'. But on his return from Australia, he 'created tension' by berating his family for their religious lapses, she said.

Mohamed tried to blow up the luxury Taj Samudra hotel (pictured) in the Sri Lankan capital Colombo on Easter Sunday

But he is believed to have botched his attempt to detonate his bomb at the five-star hotel and is thought to have blown himself up by accident at a much smaller guest house (pictured)

'I had many arguments with him,' his sister recalled. 'At first he started quoting scripture and I would say OK, you're right.

'But then the conversation got deeper and deeper into religion and I couldn't follow what he was saying any longer.

'He told male relatives off for trimming their beards and became angry and totally crazy. So I just stopped speaking to him because it got to the point where it was getting out of hand.'

Although Mohamed lived round the corner, the siblings avoided each other. She he came to visit their mother, who lived with Mrs Hidaya, he would ignore her.

'We even started using different roads to go to and from our houses,' she said.

But despite his evident fanaticism, the news of the Easter atrocities came as a shock. 'When the police came to tell us it was him, I almost collapsed,' Mrs Hidaya said.

'I just didn't think he would take it this far. I am still in disbelief. Something happened to him in Australia that changed his personality. He became silent and aloof.'

Mohamed's wife, who he married in a lavish ceremony before moving to Australia, was a 'silent and anonymous' character, Mrs Hidaya said.

She has been taken into police custody and their four children, aged six, four, two and six months, are being cared for by their grandmother in the home where the atrocity was planned.

Mohamed's identity came to light after Sri Lanka's defence minister, Ruwan Wijewardene, told a media briefing earlier on Wednesday that one of the bombers had studied in the UK and done postgraduate studies in Australia before returning to settle in Sri Lanka.

Mrs Hidaya said her brother, born in 1982 to a family with six siblings, was from a wealthy tea trading family based near the central city of Kandy.

He was educated at the nearby Gampola International School before studying for his A Levels at the Royal Institute, a well-known international school in Colombo.

Ten years ago, after his father, Abdul Latif, died, his mother, Samsun Nissa, moved the family to Colombo, renting the upper floor of a mansion in a majority Muslim eastern suburb.

After returning from studying in Britain, he moved into the property and fell in love with their landlord's daughter, Shifana, who came from an affluent meat-trading family.

They married before moving to Australia so he could pursue his postgraduate studies.

Mohamed, who had his first child in Australia where he is believed to have become radicalised, moved back to Sri Lanka to live in the mansion (pictured) his family previously rented

Mohamed's younger sister married a Sri Lankan New Zealander and emigrated to Auckland with their mother.

Her brother, who had his first child in Australia, moved back to Sri Lanka to live in the mansion his family previously rented.

His grandfather had left him an extensive property portfolio when he died, including the family home in Kandy. As a result, the trained aeronautical engineer did not need to work.

'Before he died he was selling the family home,' Mrs Hidaya said. 'He obviously needed a sum of money.

'But he never wanted for anything in his life. From time to time he sold or bought a property. He never had to worry about money like ordinary people do.'