The Saudi embassy in London reported that Khalid Masood, the terrorist responsible for killing 4 people and injuring 40 at the UK parliament, visited Saudi Arabia three times, but was on no security watch list. His visits took place from November 2005 to November 2006 and April 2008 to April 2009, when he worked as an English teacher on a work visa," and again in March 2015. The embassy offered assistance to the British police in defeating terrorism
How Masood became radicalized is not clear. His visits to Saudi Arabia may provide clues. It is also thought that during one of his stints in prison for various criminal offensives, he was exposed to radical views.