Wellington, May 4 (IANS): The Auckland-based mother and sister of one of the Sri Lankan Easter Sunday suicide bombers have been "cooperating fully" with the New Zealand police following the attacks that killed over 250 people.

Abdul Lathief Jameel Mohamed was to blow up the luxury Taj Samudra hotel in the Sri Lankan capital Colombo. He, however, is believed to have botched the attempt to detonate bomb at the five-star hotel and instead blew himself up at a nearby budget motel, killing 2 guests who had just arrived.

Mohamed's mother, sister and her husband live in a modest house in southern Auckland. They refused to comment on the extent of their involvement in the suicide bombings' investigation, which involves the New Zealand police and Sri Lankan authorities.

"We only cooperate with the (New Zealand) police, no matter what they want to know, that's about it," Mohamed's brother-in-law told the New Zealand Herald on Saturday.

According to a report by the daily, 10 years ago, after the death of Mohamed's father Abdul Latif, his mother Samsun Nissa moved the family to Colombo, renting the upper floor of a mansion in a majority Muslim eastern suburb.

After completing his studies in Britain, Mohamed returned to the property and fell in love with Shifana, daughter of their landlord who came from an affluent meat-trading family. Mohamed married her and shifted to Australia with her to pursue postgraduate studies.

Mohamed's sister, meanwhile, married a Sri Lankan and emigrated to Auckland along with her mother.

Mohamed, who had his first child in Australia, later returned to Sri Lanka to live in the mansion his family previously rented. His grandfather had left him an extensive property portfolio, including the family home in Kandy.

As a result, the trained aeronautical engineer did not need to work.

The bomber's sister said Mohamed had been well educated but became increasingly withdrawn and intense as he descended into extremism. "My brother became deeply, deeply religious while he was in Australia. After he did his postgraduation in Australia, he returned to Sri Lanka a different man.

"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 He became serious and withdrawn and would not even smile at anyone he didn't know, let alone laugh," she said.