A hacker who used a Trojan horse program to take control of computers belonging to adolescent girls in the United Kingdom\u00a0and Canada was sentenced to 10 years in prison on Thursday, prosecutors in London said.Adrian Ringland, 36, of Ilkeston, Derbyshire, admitted to sending Trojan horse applications through Microsoft\u2019s instant-messaging program to the girls, which then allowed him to control their computers, according to a Crown Prosecution Service (CPS) spokeswoman. The girls, whom Ringland met through chat rooms, were between 13 and 16 years old.He demonstrated his control of the girls\u2019 computers by remotely opening and closing the disc drive or turning off the monitor, while pressuring his victims to send naked photos of themselves. Having obtained the photos, he then threatened to disclose them to the girls\u2019 friends and family using contact information he had stolen from the machines, unless they sent\u00a0additional photos.One of Ringland\u2019s victims sent a photo of herself topless, which Ringland then posted as wallpaper on her computer\u2019s desktop."It was to prove the power he had to help him with blackmail," the CPS official said.Ringland pleaded guilty to two counts of unauthorized modification of a computer under the Computer Misuse Act, three counts of blackmail, six counts of making indecent photos of children and one count of indecency with a child. Ringland was eventually reported to the Royal Canadian Mounted Police, which started an investigation that included the U.S. FBI, Microsoft and Britain\u2019s Serious Organized Crime Agency, the CPS official said.-Jeremy Kirk, IDG News Service (London Bureau)Check out our CIO News Alerts and Tech Informer pages for more updated news coverage.