A British teenager involved in making false bomb threats and launching distributed denial-of-service (DDoS) attacks has been sentenced to three years in prison.

The bomb hoaxes of George Duke-Cohan, aged 19, targeted thousands of schools and other organizations in the United States and the United Kingdom, in hundreds of cases resulting in evacuations. He also made a prank call claiming that a United Airlines flight traveling from the UK to San Francisco had been hijacked.

The prank call targeting San Francisco airport was made while Duke-Cohan was on bail following his arrest – during that time he was not allowed to use electronic devices.

He has now been sentenced to one year in prison for the bomb hoaxes targeting schools, and two years for the airport incident.

While the charges brought against Duke-Cohan in the U.K. focused on the pranks, the teen was said to be the leader of Apophis Squad, a group that not only made bomb threats, but also launched DDoS attacks and offered DDoS-for-hire services.

The DDoS attack targets included security blogger Brian Krebs, the DEF CON security conference, government organizations in several countries, and the encrypted email provider Protonmail, which helped authorities identify Duke-Cohan and other members of his group.

Duke-Cohan is said to face additional charges in the United States, but an indictment has yet to be announced.

Before sentencing, the judge noted that Duke-Cohan’s early guilty pleas, his age, no prior criminal record and, to a limited extent, his “functioning deficiencies which have contributed to a diagnosis of autism,” were taken into consideration. However, these mitigating factors only helped his case to a certain degree.

“You knew exactly what you were doing and why you were doing it, and you knew full well the havoc that would follow,” Judge Richard Foster said, quoted by the Daily Mail. “What you did was far removed from anything that could be described as naivety or a cry for help from a sick person.”

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