Commissioner Peter Marshall conceded his staff could have been "sharper" and one of the country's most senior female cops Detective Inspector Karyn Malthus was sent to take over the case.
Shortly after she announced the formation of a multi-agency team dubbed Operation Clover, which would work together on the Roast Busters case.
Ms Malthus has refused to say exactly what that team are doing to resolve the case. But she told the Herald that the investigation had continued over Christmas and New Year.
"It is a comprehensive and lengthy investigation and the focus for the joint agency Operation Clover team continues to be on speaking to young people and their parents," she said.
"It is of the utmost importance that the privacy, health and wellbeing of these young people is strictly upheld. We appreciate the high level of public interest in this case, however, as is routine with an investigation of this nature, we will not discuss any operational aspects and no further comment will be made at this time."
Anyone with information about the Roast Busters case, or any victim that wants to make a complaint to police can contact the Operation Clover team on 0800 OP CLOVER (0800 672 568).