A second secret informant - Witness B - who testified in David Tamihere's double-murder trial nearly 30 years ago can now be revealed.

Witness B's unmasking comes just hours after the Herald and other media organisations unveiled Witness C as Roberto Conchie Harris.

Witness B is the late Stephen Kapa.

He was one of three prison snitches that the Crown relied on to give "powerful" evidence during the 1990 jury trial, which saw Tamihere found guilty of murdering Swedish tourists Urban Hoglin, 23, and Heidi Paakkonen, 21, in the Coromandel Ranges in 1989.

Witness A is now the only prison informant of the three snitches to still enjoy identity suppression from Tamihere's trial.

However, his exact location and wellbeing is unknown despite speculation the informant may now be overseas, possibly in Fiji.

The prisoners all claimed Tamihere had, at different times, while in custody, confessed to how he sexually assaulted and killed the Swedes.

Inmate Arthur Taylor, who was behind the perjury prosecution of Harris, also argued for Witness B's name suppression to be revoked.

Justice Mark Woolford removed the veil on Kapa, revoking the suppression order made on November 20, 1990, by trial judge Justice David Tompkins. It was due to come into effect from May 1, to allow the Crown, which opposed the order, to seek further legal options.

"The events that followed the Tamihere trial, including Witness C's convictions for perjury, also take this case outside the norm. The public interest now requires a free exchange of information and opinions. The principle of open justice should prevail," Justice Woolford said.

However, last night, as news of Harris' past and malignant offending was made public, Taylor filed a memorandum in the High Court seeking that Witness B's name be unsuppressed immediately.

Justice Woolford quickly granted the application - allowing publication of Kapa's name.

Kapa died in a car crash on February 18, 1995.

Further information about his past and his time spent in prison is currently being sought by the Herald from the Department of Corrections under Official Information Act.

Taylor believes Kapa, like Harris, lied during Tamihere's trial and that Kapa never met the man convicted of killing the Swedish backpackers while both were in prison during the late 1980s.

The "jailhouse lawyer" said he would "quite possibly" have launched a private prosecution against Kapa, as he did against Harris, if the prison snitch was still alive, he told Justice Woolford during a hearing about Kapa's name suppression last month.

It is a claim refuted by the Crown, which points to the evidence of a Mt Eden Prison officer who testified during Tamihere's trial about prisoner movements, meaning Tamihere and Kapa may have met between July 7-11, 1989.

Kapa's family still reside in New Zealand, the court heard at the March hearing.

Justice Woolford said Kapa no longer requires the protection of a suppression order and there was no specific threat or danger to his family.

The Court of Appeal has also described the trio's evidence against Tamihere as "wholly circumstantial".

Minister of Justice Andrew Little talked about prison informants with the Herald last night and said: "We've seen so many cases now where jailhouse snitches have proven to be, frankly, abject liars and from a justice system point of view it's a waste of time and resources to have cases reliant on their evidence, and I think it's time to review that.

"It is a matter for police and Crown Law to see if they want to continue to have jailhouse snitches. We should have a closer look to see if this practice should continue."

Tamihere was sentenced to life imprisonment after his trial nearly three decades ago. He has had all his appeals rejected, and was denied leave to appeal to the Privy Council.

Eventually he was released on parole in 2010 but always professed his innocence.

He has, however, not ruled out a prerogative of mercy application.

In 1991, Hoglin's remains were discovered by pig hunters in bush near Whangamata, about 70km from where the murders were alleged to have taken place.

Paakkonen's remains have never been found.