A student who made hundreds of thousands of pounds blackmailing the users of porn sites around the world as part of the UK’s most serious cyber crime case, has been jailed for six-and-a-half years.Zain Qaiser, 24, who operated out of his bedroom at his parents’ home in Barking, east London, worked with a Russian crime group to infect millions of computers with viruses that locked them out of their machines.He then claimed to be a member of the local law enforcement agency and demanded a payment of more than £750 in order to unfreeze their screens.Qaiser is estimated to have raked in more than £700,000 between 2012 and 2014, spending the proceeds on expensive watches, luxury hotel stays and regular trips to casinos.The National Crime Agency, which investigated Qaiser’s activities, said it was impossible to know how many victims he had successfully targeted, but described the case as the most serious cyber crime investigation it had ever undertaken. “It has been asserted on your behalf you are remorseful. I have seen no outward expression of that.”Qaiser, who initially denied the crimes and claimed he had been hacked himself, remained expressionless as he was sentenced.Nigel Leary, a senior NCA investigating officer, said: “Zain Qaiser was an integral part of this organised crime group generating millions of pounds in ransom payments by blackmailing countless victims and threatening them with bogus police investigations.”The FBI and the US Secret Service have both arrested people in relation to this global malware campaign.”The investigation demonstrates that cyber criminals cannot operate from behind a veil of anonymity and that the NCA has the tenacity and specialist skills to catch them and bring them to justice.”Qaiser entered guilty pleas to an 11-count indictment, admitting three counts of blackmail; three counts of fraud by false representation; four counts of doing an unauthorised act with intent to impair the operation of a computer; and one count of possessing criminal property. But when users clicked on the adverts their computers were exposed to a highly sophisticated virus known as Angler software.The infected computers then displayed a message which purported to be from the local law enforcement agency and warned the user that they had committed an offence and had to pay $1,000 (£767).The victims spanned at least 20 countries and the crime group for which Qaiser was working are thought to have generated millions of pounds in ransoms. “All the constituent offences were part and parcel of your role as the self-styled ‘K!NG’ of the internet. The money was paid through an online currency which could then be put onto pre-loaded credit cards.It was then withdrawn in cash abroad by others in the network and redirected through online currency services.While some of the advertising companies Qaiser was buying space from turned a blind eye to his activities, ones who challenged him were targeted with cyber attacks including threats that they would be bombarded with indecent images of children.The resulting lost business ended up costing some companies hundreds of thousands of pounds.Qaiser had initially acted alone but later contacted the Russian crime syndicate offering his services as an English speaker and expert in the online advertising industry.Sentencing him to six and a half years, Judge Timothy Lamb QC, said: “The harm caused by your offending was extensive – so extensive that there does not appear to be a reported case involving anything comparable. The former computer science student committed most of his crimes when he was still a teenager, but the complexity of the case meant it took more than four years to bring Qaiser to justice.Using the online name K!NG, he posed as a legitimate businessman to buy large amounts of advertising space on pornographic websites. CCTV captured Qaiser cashing in some of his money at a casinoCredit:Universal News Qaiser blackmailed porn website users after using malware to lock their computer screensCredit:NCA/PA Qaiser was charged following the UK’s most serious cyber crime investigation, according to the National Crime AgencyCredit:Ed Willcox Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.