Police Minister Anne Tolley has been assured by Police Commissioner Peter Marshall that the force has been "actively working" to build a case against a group of men who shamed drunk teen girls they allegedly lured into group sex.
Police today said they had brought in a senior detective from outside the Waitemata district to help.
The detective would provide extra support during the ongoing investigaton into the Roast Busters - a group of Auckland men, understood to be aged 17 and 18, who allegedly had group sex with drunk teenage girls and bragged about it online.
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Police also today denied suggestions the inquiry was affected by the involvement of an officer's son. There has been criticism that the police investigation has taken too long, given the first allegations were brought to their attention two years ago.
"NZ police take any allegations of criminal offending by any of its officers or their families extremely seriously," Waitemata Police District Commander Superintendent Bill Searle said.
"Recent cases have highlighted that police will not hesitate to thoroughly investigate staff facing allegations of a criminal nature and will put them before the court if there is a case to answer."
Tolley said her understanding was the Facebook page wasn't up for the entire two years.
"It was down for a considerable period of time and has only just recently come back up again.
"I've been assured by the Commissioner that they have been very active for the last couple of years, trying to investigate and gather enough evidence to bring charges against these young people."
Tolley said she understood it had been "frustrating" for police.
"There is an enormous amount of support I know the police will be making sure is available to these young girls.
"But it's a very difficult thing for young women to come forward and talk about what's happened to them. It's embarrassing, it's frightening, the legal system itself can be overwhelming so I think we just have to continue to urge them and their families to get the courage to come forward and enable the police to take a case against these young men."
Police have also condemned the actions of several vigilante groups which have posted threats on social media.
Thousands of outraged internet users were questioning why the group was allowed to operate almost unchecked for two years.
Several Facebook groups were threatening vigilante action against the Auckland men.
One Facebook group saying the gang deserved to ''rot in jail'' had attracted more than 18,000 likes this morning. Others posted threats of violence against the teenagers.
"We understand the outrage that this group has caused, however violence will not be tolerated and we will take firm action against anyone inciting, threatening or using violence against these people," Searle said.
Meanwhile Joseph Levall Parker - the son of Hollywood actor Anthony Ray Parker - has lost his job at an Auckland real estate office amid the furore, The Herald reported. His family told TV3 he left the gang months ago.
Images of another gang member, Beraiah Hales, were circulating widely online. He didn't respond to internet messages and has shut down his main Facebook page, though two others are still in operation.
Earlier this year someone claiming to be Hales went on a social media website to defend the group, saying they hadn't done anything illegal and they had "already been to the police about that... and I'm not going to jail".
An ex-girlfriend defended Hales on the same social media website, writing that they weren't rapists and "nobody knows them well enough to judge them".
She wrote the girls involved "lied" about their ages, "allowed it all to happen" and that most "went back for more". She claimed that they were only upset because the boys didn't acknowledge them afterwards.
One of the boys is the son of a police officer, TV3 and the Herald reported.
Police were criticised for keeping the Facebook page open, but Detective Inspector Bruce Scott said it enabled them to monitor information.
Police have been monitoring the Roast Busters Facebook page for months, and were aware of the group for two years after being informally approached by a victim.
Police have also alerted the high school that the suspects were attending.
They had interviewed two men over the allegations but said yesterday there was not enough evidence to press charges at this stage.
"We're grateful that the publicity around this case has enabled us to make further progress, and we hope to build on the work done by the enquiry team to potentially take us to the stage where we have enough evidence to build a case," Scott said.
The principal of one school where some of the students involved are understood have attended said delays in apprehending the culprits is "frustrating".
"It is extremely frustrating when the perpetrators cannot be held to account, even when they brag openly about their actions in a public forum," principal Morag Hutchinson said.
"We look to the law to protect us all, but especially those who are vulnerable because of their youth and naivety."
Meanwhile Rape Prevention Education national advocate Louise Nicholas is reaching out to victims apprehensive about going to police.
Nicholas said any of the girls and their family and friends can contact her to ask questions about the process of laying a complaint. "It doesn't mean you have to go to police right away, everything is in your own time. It's important they know there is support for them."
Prime Minister John Key condemned the alleged actions of the gang as "extremely disturbing and disgusting behaviour".
"These young guys should just grow up," Key said yesterday.