Warning: This story contains graphic and distressing details of animal cruelty and references to child abuse.

A globally distinguished crocodile expert and zoologist who raped, tortured and killed dozens of dogs and puppies on his rural property on the fringes of Darwin has had his case delayed again, angering animal rights activists.

Adam Britton pleaded guilty to more than 60 charges of bestiality, animal cruelty and possession of child abuse material last year

According to the agreed facts, in a shipping container on his property dubbed his "torture room", Britton filmed himself sexually exploiting and then beating to death dogs he sourced for free on online classifieds giant Gumtree.

Between 2020 and his arrest two years later, Britton is known to have killed at least 39 dogs, but his offending is understood to date back to 2014.

In the NT Supreme Court on Thursday, dozens of animal rights activists filled the gallery to witness Britton's sentencing.

In a rare occurrence inside a courtroom, Judge Michael Grant told court staff to leave and warned others to follow suit, describing the offending as "grotesque cruelty to animals".

"In my assessment, the material has the potential to cause nervous shock or some other psychological disturbance," he said.

But the chilling details of the offending, which the ABC has chosen to limit due to their graphic nature, were not heard.

Britton's defence lawyer — who asked not to be named after receiving threats for representing their client — asked the judge to consider a new report following Britton receiving "nearly 30 hours of treatment by a psychologist" within prison.

They said the report showed Britton now felt remorse for his crimes.

"Remorse is considered evidence of rehabilitative prospects, as is insight," Britton's lawyer told the court.

"Those are things that may not be present the first time that someone speaks to someone in a professional capacity. They are things that often evolve with treatment. They're not fixed in stone."

Britton's lawyer also argued that his early guilty plea and cooperation with police warranted a reduced sentence.

"This is a human being who has been afflicted by a condition since very early childhood … it is not his fault," Britton's lawyer said.

"It's of significance, your honour, that this particular condition is exceptionally taboo in most societies, and the court can, I hope, accept that that would have been a very difficult thing to grow up with and learn to manage into adulthood."

On the free messenger service Telegram, Britton discussed his kill count and uploaded videos of his murders under the pseudonyms 'Monster' and 'Cerberus'.

In his submissions, Crown Prosecutor Marty Aust argued there was "significant planning" in Britton's "sadistic sexual violence", involving multiple cameras, tripods, and efforts to conceal his identity.

"If we watch that footage, you will see the extreme pleasure and enjoyment that this man had in creating this and doing these acts," Mr Aust said.