TV doco on Emma Agnew's murderer goes to air tonight

A TV documentary that convicted murderer and rapist Liam Reid tried to stop going to air will screen on television this evening.

The show is part of the Forensics NZ series, by South Pacific Pictures, running on Prime at 8.30pm.

It examines the police investigation that led to Reid's conviction.

Reid is serving a life sentence with a 23-year minimum non parole period for raping and killing deaf woman Emma Agnew in Christchurch in 2007.

He was also convicted of the rape, attempted murder and robbery of a 21-year-old student in Dunedin nine days later.

Reid sought an injunction against the South Pacific production about the forensic evidence used to convict him of his crimes against Agnew.

It was argued for him that the show could pose a risk to any future appeal or retrial.

Reid has indicated he wants to apply to the Governor-General for her to exercise the royal prerogative of mercy.

"I have always maintained my innocence in relation to the Christchurch matter and the Dunedin matter," Reid said in a sworn statement for the injunction hearing in the High Court at Auckland in February.

Following his 2008 convictions, his appeal was dismissed by the Court of Appeal in 2009. In 2012, the Supreme Court rejected his bid to appeal further.

South Pacific says the show will contain details of the investigation that were not reported by media at the time.

Rachael Keereweer, the company's head of communications, said one example of this was to do with Agnew's car.

"There was some specific evidence regarding some hair [of Reid's] left in the car."

For the injunction hearing, Reid's lawyer Jeremy Bioletti said the core issues of the intended appeal were cellphone evidence and a hair found in Agnew's vehicle.

DNA testing revealed the hair was Reid's.

Bioletti wanted cellphone evidence examined by an independent expert and there were chain-of-custody issues with the hair, he said. There were also core forensic issues in the Dunedin case.