A 17-year-old, whose name has not been released due to his age, has been found guilty of plotting a terrorist attack at a June 30 Justin Bieber concert that took place in Wales' capital city Cardiff. The teen, who is reportedly white and British, was arrested on the day of the concert, which took place at Principality Stadium (which you may know by its former name, Millennium Stadium).

During the course of his trial, it was reported that the teen was found with a "martyrdom letter" which had details of the attack he had planned. It was also reported that the teen had set up an Instagram account which encouraged jihad and supported al Qaeda. His password for that account was "truck attack." 

According to police, the boy had carried out a number of online searches which explored how best to drive a vehicle into a crowd before getting out and stabbing nearby pedestrians. In addition to the "martyrdom letter" that he had on him at the time of his arrest, he also had a knife and hammer in his backpack, and stated that he was a "solider of the Islamic state." Prosecutors also argued that he checked around online for details on the Bieber concert's security procedures.

In his defense, his attorney said that he was not actually planning an attack, but that he had a "stupid interest in the gory." The boy also told the jury that his curiosity led him to check how easy it was to look up terror-related topics on the internet.

According to the BBC, he was found guilty of "one charge of engaging in the preparation of a terrorist act, two charges of encouraging terrorism [and] two charges of possessing terrorist information." He will be sentenced during a hearing on January 10.