A renowned British crocodile expert has been jailed for 10 years and five months in Australia, after admitting to sexually abusing dozens of dogs, in a case which horrified the nation.

Warning: This story contains details readers might find distressing

Adam Britton, a leading zoologist who has worked on BBC and National Geographic productions, pleaded guilty to 56 charges relating to bestiality and animal cruelty.

He also admitted to four counts of accessing child abuse material.

The Northern Territory (NT) Supreme Court heard the 53-year-old filmed himself torturing the animals until almost all died, and then shared the videos online under pseudonyms.

His abuse went unnoticed for years, until a clue was found in one of his videos. Britton was arrested in April 2022 after a search of his rural Darwin property, which also uncovered child abuse material on his laptop.

Much of the detail of Britton’s crimes are too graphic to publish, and so “grotesque” Chief Justice Michael Grant warned the courtroom they could cause “nervous shock”.

As the facts of the case were read aloud, some members of the public rushed outside. Others watching from the gallery cried and mouthed insults at Britton. He at times hung his head and reached for tissues.

Calling the offending “devious”, Justice Grant said the “unalloyed pleasure” Britton took in torturing the animals was “sickeningly evident”.

“[Your] depravity falls entirely outside any ordinary human conception,” he said.

Including time already served, Britton could be eligible for parole in September 2028. He is also banned from owning any mammals for the rest of his life.

Mr Britton’s lawyer argued his offending was driven by a rare disorder causing intense, atypical sexual interests.

In court on Thursday, they read out a letter from Britton, who apologised for his “demeaning crimes”.

“I deeply regret the pain and trauma that I caused to innocent animals and consequently to my family, friends and members of the community,” it said.

Adding that his family was not aware or involved in any way, he wrote: “I will seek long term treatment and… I will find a path towards redemption.”

Born in West Yorkshire, Britton grew up in the UK before moving to Australia more than 20 years ago to work with crocodiles.

With a PhD in zoology, he had built a global reputation for his expertise, even hosting Sir David Attenborough while the veteran broadcaster filmed part of the Life in Cold Blood docuseries on his property.

Locals have told media he seemed like a quiet but passionate defender of animals.

But he was harbouring a “sadistic sexual interest” in them, court documents say. Exchanges with “like-minded” people in secret online chatrooms detail how Britton began molesting horses at the age of 13.

“I was sadistic as a child to animals, but I had repressed it. In the last few years I let it out again, and now I can’t stop. I don’t want to. :),” he wrote in one message tendered to the court.

For at least the past decade, Britton had exploited his own pets and manipulated other dog owners into giving him theirs.

“My own dogs are family and I have limits,” he explained in a Telegram chat entered into evidence.

“I only badly mistreat other dogs… I have no emotional bond to them, they are toys pure and simple. And [there are] plenty more where they came from.”

He tortured at least 42 dogs, killing 39 of them, according to court documents seen by the BBC. The files only detail his crimes over the 18 months before his arrest, but still fill more than 90 pages.

Using online marketplace Gumtree Australia, Britton would find people who were often reluctantly giving their pets away due to travel or work commitments. He would build a “rapport” with them to negotiate taking custody of the animals and if they reached out for updates on their old pets, the court heard he would tell them “false narratives” and send them old photos.

In reality, he was abusing the animals in a shipping container on his property that had been fitted out with recording equipment – which he called his “torture room” – before sharing footage of his crimes online using aliases.

Britton would also coach others on how to copy his behaviour and get rid of the evidence.

Asked how to dispose of the dogs’ remains, Britton – who shared his sprawling property on the outskirts of Darwin with eight crocodiles – said “some I feed to other animals”.

He was only caught after uploading a clip in which he tortured at least eight dogs – all except one were puppies – which was passed on to NT police in an anonymous tip-off.

Britton usually went to great lengths to avoid identifying himself or his location in his videos, but in this one a bright orange City of Darwin dog leash could be seen in the background.

Within weeks, in April 2022, police swooped on his property and arrested Britton, who has been remanded in custody ever since.

They seized recording devices, animal remains and a laptop on which they also located 15 files containing child abuse material.

Animal advocates say the case shows the need for stronger animal cruelty penalties.

Speaking outside court, many who had travelled from all over the country for the hearing expressed disappointment at the sentence, but said it offered some solace to the owners of the pets Britton abused.

Addressing the zoologist directly, one activist told Britton he was “right where you should be – locked up.”

“Once respected and esteemed, you’re now a disgrace to the scientific community,” said Natalie Carey. “No one will ever look at you with admiration again.”