A teenager has been found responsible for a hacking spree in which victims’ savings were stolen and major companies, including the maker of the best-selling Grand Theft Auto video games, were blackmailed.

Arion Kurtaj, 18, from Oxford and a 17-year-old who cannot be named for legal reasons, were described by the prosecution as the “key players” in the LapsusS hacking group.

Psychiatrists had assessed Kurtaj as unfit to stand trial so the role of the jury in his case was to decide whether he had committed the acts alleged against him.

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On Wednesday, following a two-month trial at London’s Southwark Crown Court, a jury unanimously found Kurtaj had carried out 12 offences in his spree of innovative hacks.

These offences included six counts of carrying out an unauthorised act to impair the operation of a computer, three counts of blackmail, two fraud offences, and of failing to comply with a section 49 notice to disclose a key when he did not give up the password to his mobile phone when asked to by police.

He tried to blackmail Rockstar Games by threatening to “leak the stolen source code for the Grand Theft Auto sequel onto internet forums”, the indictment stated.

Kurtaj and the youth were also accused of hacking software company Nvidia in February 2022 before threatening to “release Nvidia Corporation’s intellectual property on to the web” if it did not pay them.

The 17 year-old showed no emotion as he was found guilty of one count of fraud, a charge of blackmail and also of having carried out an unauthorised act to impair the operation of a computer.

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His mother wept uncontrollably after the verdicts were read out.

Prosecutors alleged Kurtaj and the 17-year-old, aided by unknown associates, hacked the servers and data files of broadband provider BT and mobile operator EE before demanding a four million US dollar ransom on August 1, 2021.

But the 17-year-old was found not guilty of a charge of have carried out an unauthorised act to impair the operation of a computer and a further charge of blackmail in relation to BT.

He previously pleaded guilty to one offence under the Computer Misuse Act and one count of fraud.

Neither defendant gave evidence during the jury trial.

Sentencing dates at the same court have yet to be fixed for either defendant.

A case management hearing has been set for Kurtaj on September 21, while it is hoped that a sentencing date may be fixed for the 17 year-old on November 9.