The first successful conviction of a "hurtcore" paedophile has been described as a "watershed" moment for British police as they respond to new technologies that give criminals opportunities to increase the scale and depravity of child abuse.
Dr Matthew Falder, a Cambridge University graduate, used his "evilmind" and "666devil" accounts on encrypted dark web forums to coerce, control and ultimately devastate his victims.
And he is not alone, investigators at the National Crime Agency (NCA) warned.
Will Kerr, NCA director of vulnerabilities, said police are increasingly concerned about what he described as "horrific" crimes, which are often done for profit and linked to organised gangs, and which required "unprecedented" levels of resources to stop.
The NCA, working with UK police forces, government listening post GCHQ, US Homeland Security, the Australian Federal Police and Europol, needed up to 100 investigators to find, track and detain Falder, who had managed to evade detection for nearly four years.
Mr Kerr said: "It's a bit of a watershed moment this investigation for policing for two principal reasons, one it highlights a previously unknown level of very horrific offending - there were over 300 contact reports from Matthew Falder alone.
"Secondly, it also highlights the unprecedented level of resources that law enforcement has to put into these investigations - at one point there were 100 investigators working on this case using the broadest range of new covert capabilities to try and identify and catch him and his other offenders who were engaged in similar activity.
"Falder is not alone - there are many other users of some of these dark web sites and we are very concerned about it."
The Birmingham University researcher's conviction comes amid a backdrop of constant police action against paedophiles and a change in social norms that has seen young people spend more and more time online.
A UK-wide sting operation in October saw 192 suspects arrested and 245 children saved from harm, while Mr Kerr said police are arresting 400 people and safeguarding 500 children on a routine basis every month.
But two elements have come to characterise child sex exploitation and abuse (CSEA) online in the last few years, Mr Kerr said - the abundance of indecent images of children online and the new type of "higher harm" offences including live streaming and dark web-enabled blackmail.
"Since the NCA was created in 2013 we have seen a 700% increase in the number of referrals for indecent images of children and young people coming to us as the national agency," he said.
"(There was) a 44 per cent increase this year alone so the proliferation of images online has been a significant challenge for law enforcement over the last number of years.
"But that proliferation of images has led to a very significant increase in law enforcement and policing response across the UK to respond to it.
"The Child Abuse Image Database launched a few years ago but now has eight-and-a-half million images on it."
The NCA launched a campaign to raise awareness of the dangers of live streaming in November and Mr Kerr said this technology was enabling paedophiles to engage in what police traditionally refer to as "contact" offences with their victims.
He said: "What we've also seen running in parallel to that massive and continued increase in images being referred to law enforcement and indecent images of children and young people being shared online has been an increasing use of encrypted online new and emerging platforms where offenders are able to hide their activity.
"They are able to use anonymising software to engage in a range of offending which is increasingly intended to engage in contact abuse with children.
"We are also concerned about some new offences that five, six years ago weren't a challenge for law enforcement - they've only really become a significant concern for us over the last few years as these new and emerging platforms have developed.
"So live streaming, particularly in the Far East, we see the live streaming of contact abuse of children, some as young as babies and toddlers done to order and by organised crime gangs operating in the Far East.
"The difference of course in that type of offending is it adds a new very complex and very worrying layer to the number of CSEA offences worldwide because of course it's not just done on the basis of sexual predilection or satisfaction - it is done for profit."