Anti terror police managed to stop Lloyd Gunton, 17, hours before he was planning to launch a knife and hammer terror attack on a Justin Bieber concert on June 30, 2017.
Gunton wrote a so-called martyrdom letter ahead of the concert at the Principality Stadium in Cardiff.
Officers arrested Gunton at his home in Llanstrisant, south Wales, hours before the planned attack.
Gunton - who is on the autism spectrum - was jailed for life in March and ordered to serve a minimum of 11 years.
Lloyd Gunton, pictured, was 17 years of age when he planned to launch a hammer and knife terror attack on an Justin Bieber concert in Cardiff in June 2017
Muthana was a 20-year-old medical student when he left his home in Cardiff and went to Sryia to join ISIS.
He was believed to be part of an ISIS death squad and appeared in a recruitment video for the terrorrist organisation in June 2014.
He was also believed to have been involved in the murder of 26-year-old American aid worker Peter Kassig.
Authorities believe Muthana's younger brother Aseel, who was 17 in 2014, also went to