Police have questioned whether murder accused Chris Kahui is the biological father of dead twins Chris and Cru - and will use the twins' mother to testify against him in court.
The Herald on Sunday also understands that police bugged telephone conversations between Chris and his former partner Macsyna King in the lead-up to his arrest last week.
Family members confirmed yesterday that police had questioned them over the twins' paternity, but they were adamant that Chris Kahui was the father. "We believe he is the father and that he did nothing wrong," said Kahui's sister Mona-Louise, speaking publicly for the first time yesterday.
She was one of four family members living in the Mangere home when the twins were fatally injured.
"Nobody knows my brother like we do, and he's innocent. We don't care what anyone else thinks, we'll give the answers when we get them."
Police would not comment yesterday, but a source close to the investigation said officers had bugged telephone arguments between Chris and Macsyna, who separated in August.
The Herald on Sunday can also reveal that police believed they had enough information to charge Chris Kahui with killing the twins even before they brought him in for questioning on Thursday.
Information hidden in the computer code of an emailed press release from police revealed that Chris Kahui's fate was sealed even before he was picked up for questioning. The release was sent out by Counties Manukau police spokeswoman Angeline Barlaw at 10.20pm on Thursday, October 26. It announced the arrest of "a 21-year-old male for the murder of the twin babies" and came from Detective Senior Sergeant John Tims.
But computer data recorded in the Microsoft Word file showed that Tims had actually created the file to write the press release on Saturday last week.
Other data showed that Tims had finished writing and had saved the document for the final time on October 25 - the day before Chris Kahui was brought in for questioning. Tims refused to comment on the timing of the release, but the source said the questioning was simply to make Kahui "cough".
"They just wanted to lay all their cards on the table in the hope that he'd confess. But he didn't."
It is also believed that police feared Kahui would hurt himself without his lawyer Lorraine Smith present, as she was on holiday in Australia. She refused to divulge Kahui's state of mind or to say whether he was on suicide watch in prison.
"Chris is in a state of shock. He trusts the police, he believes in the justice system, but he can't understand how they got the wrong person," Smith said.