One of Britain's worst ever paedophiles is facing life in jail after pleading guilty to raping and sexually abusing dozens of children in south east Asia for almost a decade.
Former grammar schoolboy Richard Huckle, 30, from Ashford, Kent, targeted poverty-stricken communities in Malaysia and Cambodia, and - after winning the trust of locals - systematically abused boys and girls as young as 6 months old.
While he admits raping and molesting 23 youngsters, many more are thought to have fallen prey to him between 2006 and December 2014 when he was finally arrested as he returned to Britain for a Christmas holiday.
At an earlier hearing, Huckle pleaded guilty to 71 offences, 22 of which carry a maximum life sentence. Investigators from the National Crime Agency said the scale of the offending was "unprecedented and exceptional".
Huckle appeared at the Old Bailey today for a sentencing hearing that is expected to last three days.
When he initially pleaded guilty, it took the clerk of the court an hour to read the individual charges to the court.
Huckle, who worked in a mobile phone factory and posed as a committed Christian - attending churches in north London and Ashford - first went to Malaysia in 2005 on a gap year teaching placement.
The following year, he visited Cambodia and - while staying with a local family - took indecent images of their child who was aged around 3 at the time.
He then began to visit Malaysia regularly, posing as a teacher, photographer and philanthropist in order ingratiate himself with a local Christian community before raping and abusing their children.
There is no evidence at this stage that he abused any children in the UK, but the authorities have not ruled out victims coming forward.
Huckle's favourite method was to target vulnerable children in poverty-stricken communities, even boasting of his exploits to other paedophiles online.
In one posting he wrote: "Impoverished kids are definitely easier to seduce to than middle-class Western kids."
He used sick sites on the dark web to sell images of his abuse to other child molesters, accepting payment in Bitcoins.
Huckle's victims included boys, girls, toddlers, pre-teens and even babies, including one aged just 6 months old.
In one exchange found online, he wrote about "hitting the jackpot" after discovering a 3-year-old girl who he said was as "loyal as a dog".
Investigators found a posting in which he said: "I have found a 3-year-old girl who I can have so much sex with it's boring".
Huckle also kept an electronic ledger or score card on which he would award himself points according to how far his abuse had gone with a particular youngster.
While his abuse lasted almost a decade he did not come to the attention of the authorities in Britain until the middle of 2014, when the NCA received a tip from Australia about his postings on the dark web.
They began liaising with their counterparts in Malaysia but claim jurisdictional issues meant they were powerless to act while he remained overseas.
They then discovered he was planning to return to Britain for Christmas and he was arrested on December 19, 2014 when he landed at Gatwick Airport.
When detectives investigated his laptop, camera and phone they discovered more than 20,000 indecent images of young children, many featuring Huckle participating in abuse.
Prosecutors made use of Section 72 of the Sexual Offences Act that allows a UK national to be charged in Britain for offences committed overseas.
Following his arrest his parents questioned him about the allegations and he confessed to them that he was a paedophile.
His mother was described as completely devastated and his father, who works as an engineer, contacted the police and told the what he had said.
They have both given statements to the court in support of the prosecution.
Huckle initially denied all the charges and prosecutors planned on holding three separate trials because they feared the sheer volume of depraved material would be too much for one jury to deal with.
Huckle also produced a paedophile manual, called a 'child lover's guide', giving tips to other child abusers on how to avoid getting caught.
Lawyers at one legal hearing even discussed organising counselling for those forced to view the images.
But Huckle eventually pleaded guilty after accepting the weight of evidence against him.
In one particularly sick twist to the case, Huckle insisted on viewing all the online material showing his abuse before he pleaded guilty to the charges.