Former school principal and now convicted paedophile Bruce Darroch has been found guilty of four charges relating to the sexual exploitation of children.

The verdict was delivered at Rotorua District Court on Tuesday by Judge Tony Snell, who described the former Te Waotu School principal as an intelligent, articulate man who "clearly knew what child porn was".

Darroch faced six charges in total: possession of objectionable material, making an objectionable publication and two charges each of supplying objectionable material and failing to assist a police search.

After finding Darroch guilty of four charges, Snell remanded him on bail until a scheduled sentencing date of June 24.

"But be very clear, that's giving no indication as to whether you will receive a custodial sentence," he said.

Darroch was found not guilty of the charges of supplying objectionable material after Snell said it had not been proved beyond a reasonable doubt that images found on the computer of a US paedophile Darroch knew as "Administrator B" were sent by Darroch.

The images were found in a folder named "Lustboys KWB" and contained other images Darroch had sent, including photos of children at his school, plus three stories.

Snell was convinced, however, that Darroch was "Lustboys KWB".

He said other images and video clips in the folder not classified as objectionable came from Darroch's school and that stories he authored - a claim Darroch denied - also referred to boys at the school.

Snell described the stories as "graphic, detailed and with sustained rape fantasies" and dismissed claims by defence lawyer Russell Fairbrother that, as Darroch was unaware the online conversations were being recorded, that fell short of the legal definition of publication.

One of the stories related to a child at Darroch's school and a teacher.

"[The stories had] clear personal knowledge of the boy. The main character, a teacher - that is you."

Snell said the two online conversations, recorded on July 10 and 12, 2012, "promotes and supports the sexual exploitation of children".

"I am satisfied beyond a reasonable doubt that you are [Lustboys KWB]."

He also said consistencies between the content of the online conversations on the "dark web" between Darroch and Administrator B and later evidence existed, such as a type of encryption software mentioned.

Referring to the possession of objectionable material charge, Snell said "you knew full well the images were objectionable".

The photographs were found on a USB stick in the boot of Darroch's car, alongside other, encrypted material police have been unable to view.

Customs officer and forensic electronic investigator Bruce Ellis told an earlier court hearing Darroch had deleted the images after encrypting them, but he was able to recover them.

Snell also rejected Darroch's claim that it was reasonable for him to refuse to hand over passwords for a number of electronic devices to police, as that was the advice of his lawyer.

"There is no reasonable excuse existing for you not to hand over the details requested," he said.

Throughout the hour-long hearing, Darroch remained impassive in the dock. He was under the constant gaze of a number of people in the gallery.

Ahead of proceedings, Snell warned the gallery to remain silent.

"Anyone not able to contain themselves, leave now," he said.