The Independent Police Conduct Authority has found a police decision not to prosecute a group of schoolboys posting lewd pictures on social media was thorough and robust.
It also rejected comparisons with the earlier Roastbusters case.
Last year, the Herald on Sunday revealed concerns about ongoing activity by secondary pupils plying young girls with alcohol then recording sexually degrading acts before uploading images to private Facebook pages.
New Zealand Secondary Principals' Association executive member Patrick Walsh was dismayed a group of boys escaped criminal charges after running a Facebook competition where stupefied girls had photos taken with genitalia dangling over their faces.
The revelations led to high-powered meetings between police top brass and education representatives to established better lines of communication to address the issue. At the time the police said the girls involved were satisfied with how the matter was handled.
However, advocates against sexual violence considered lessons of the Roastbusters, where teenage boys plied underage girls with alcohol and boasted on Facebook about having sex with them, had been missed.
The Roastbusters inquiry revealed shortcomings in the police investigation, including a failure to pursue positive lines of inquiry and failing to consider all available offences against the young men.
In a just-released report, the police authority found comparisons with the original Roastbusters case were not justified.
It said the authority would not comment on the specific details of the more recent case, but the investigation, which ran between September and October in 2014, was robust and thorough.
"The investigation was conducted in an exemplary manner. The investigation was robust and thorough, undertaken and completed in a timely manner, and complied with law and policy," said authority chair Judge Sir David Carruthers.
"Police properly evaluated all available offences when determining the outcome of the investigation, and appropriately considered alternative action. The detective in charge of the investigation maintained excellent communication with all parties involved, including the school."
He said it was in the public interest to note that some of the information previously reported by the media was not supported by fact and comparisons with the "Roastbusters" were not justified.