They remained in custody today but Detective Inspector Virginia Le Bas refused to say whether they will be charged with murder.
"Our ultimate aim is to lay further charges," she said. "But we haven't been speaking to them again, and are dealing with other aspects of our inquiry." Ms Le Bas said the scene examination was proving to be "quite difficult", as the blaze had torn through the house.
A team of 25 officers was working on the case, and Ms Le Bas said officers had been speaking to people who knew Mr Chandrasena.
Police had also contacted the Sri Lankan consulate so they could liaise with the victim's brother who lives in nearby Christchurch.
Ms Le Bas said the brother was "extremely emotional" and was feeling "quite overwhelmed and on his own", with the rest of the family back in Sri Lanka.
"They rest of the family have been informed, but they are not planning to come to New Zealand.
"The brother is on his own in this country and is finding things very difficult. He's very upset at what has happened."
The death has rocked the quiet farming community of Oxford where Mr Chandrasena was a popular figure.
A permanent New Zealand resident, he had lived there for around four years and was a member of the local Oxford senior cricket team.
Club captain David Fulton today said the team had "just got their heads around" the fact their team-mate had died in a fire when they learned his death had become subject to a homicide probe.
He said: "We were at cricket in Rangiora yesterday and one of the guys had gone out to get an iceblock and heard over the radio that it had become a homicide inquiry.
"It was a bit of a weird feeling to hear there was more to it. We had just got our heads around that it had been an accident, and to hear it was now a homicide, there was a lot of frustration and disbelief that that could have happened to him."
Mr Fulton said the club had already spoken about organising an annual memorial match to honour Mr Chandrasena.
"Sammy was just a really good guy, who loved his cricket, always had a Sri Lankan cricket shirt on. He'd turn up on a Saturday and try and bowl fast and try and hit sixes.
"Oxford is a small place, basically a farming community and everyone knows someone who knew Sammy, so it has shocked quite a few people that something like that could happen up there."
Vic Allen, chairman for the Oxford Ward Advisory Board, said the death had come as "a bit of a surprise and a shock" for the normally peaceful town.
Police yesterday finished searches of several Christchurch properties where they believed items of clothing and property might have been dumped after the fire.
"We didn't locate anything we were looking for, but it's useful to eliminate that from our investigations," said Ms Le Bas.
Police were now interested in speaking to anyone who was travelling in or out of Christchurch early on Thursday, February 23, who may have seen a white Mitsubishi Chariot seven-seater vehicle, around the Marshlands/South Eyre/Tram roads area.
