When it came to sexually abusing children, Richard Huckle proudly fashioned himself an expert.

The Christian schoolteacher from England was so adept at taking advantage of impoverished children in Malaysia and Cambodia, he bragged online that he had authored a how-to guide for others to follow in his footsteps, according to the BBC.

"Impoverished kids are definitely much easier to seduce than middle-class Western kids," Huckle wrote in an online post cited by the BBC. "I still plan on publishing a guide on this subject sometime.”

"I'd hit the jackpot," he commented on another occasion, "a 3yo girl as loyal to me as my dog and nobody seemed to care."

When it came to preying on vulnerable children, investigators say, few have done it with more ruthless planning than Huckle.

When he was finally arrested in 2014 after eight years of terror, prosecutors accused him of raping and abusing nearly two-dozen children ranging in age from 6 months to 12 years, the BBC reported.

Police believe the total number of children victimized by Huckle is actually more than 200.

On Monday, a British judge referred to the 60-page guide titled “Pedophiles & Poverty: Child Lover Guide” as a "truly evil document," according to the BBC.

Judge Peter Rook then sentenced the 30-year-old to 22 life terms, of which he will serve a minimum of 25 years behind bars for committing 71 offenses against children, the BBC reported.

"It is very rare indeed that a judge has to sentence sexual offending by one person on such a scale as this," Rook said.

"It is also clear that, had you not been arrested, you planned to continue the same lifestyle using the expertise that you were keen to show off to and share with other abusers so as to continue your sexual exploitation of the children of such communities," he added.

Huckle — who grew up in Ashford, England — first visited Malaysia in 2005, when he was a 19-year-old on gap year, according to a recent court hearing covered by BuzzFeed.  The next year, he traveled to Cambodia, where he targeted a 4-year-old and her 6-year-old sister, BuzzFeed reported.

In both countries, Huckle cultivated an altruistic, Christian image founded upon an alleged passion for teaching English and spreading Bible stories. He posted thousands of images on Facebook showing him happily interacting with children, and he was included in a promotional video created by the British Council in Malaysia, according to BuzzFeed.

James Traynor, of the National Crime Agency's child exploitation and online protection command, told the BBC that it was all a ruse. He said Huckle intentionally traveled to a part of the world where he thought he could carry out sexual assaults on children without being caught.

His victims, the Independent noted, came mostly from poor Christian families.

"He spent several years integrating himself into the community in which he lived, making himself a trusted figure," Traynor said. "But he abused that trust in the worst possible way."

“Richard Huckle groomed those children and he groomed them to the point where he was certain that no matter what he did to them they would not tell their parents of the abuse they suffered from him,” he added.

Investigators later discovered that Huckle had amassed a library of more than 20,000 obscene images and videos documenting his assaults, which he attempted to sell on the "Dark Web" in return for Bitcoins, according to BuzzFeed.

The abuse guide was found on Huckle's laptop — in an encrypted location — and was ready for publication through "Dark Web" hyperlink, the Independent reported.

The Associated Press reported that Huckle kept a scorecard showing the number of children he'd victimized. The ledger, which had 191 names, according to Agence France Presse, had been turned into a perverse game in which Huckle awarded himself points depending on the identity of the child and the nature of the abuse.

"Under the rules," the Independent reported, "he could not receive points for the same activity with the same child in the same week."

Police were unable to file charges for each victim because many lacked photographic evidence, AFP reported.

At a recent court hearing, Huckle expressed remorse and blamed his actions on being "easily influenced" by the "pathetic, perverted list of those who drew me into the dark net," AFP reported.

“I completely misjudged the affections I received from these children," the letter said.  “My low self-esteem and lack of confidence with women was no excuse to be using these children as an outlet.”

In those same posts he penned on the Dark Web, Huckle revealed on multiple occasions the depth of his deliberation.

“As long as I keep a broad number of contacts amongst the poorer people I know, I’m sure some would be inclined for someone of ‘high status’ such as myself to be caring for their kids for long- or short-term,” he wrote, according to BuzzFeed.

During a court appearance in April, Huckle pleaded not guilty to all 91 charges against him, according to the Independent. In subsequent appearances, he admitted to 71 of the offenses, the paper reported.

On Monday, moments after Huckle's sentence was delivered, a woman in the public gallery offered him a message as he was led from the court, according to AFP.

"1,000 deaths is too good for you," she shouted.