Ali Harbi Ali, 26, was found guilty by London’s Central Criminal Court of murder and preparing terrorist acts. Ali stabbed the veteran British politician to death last year while he was meeting with voters at a church hall in eastern England.
Ali, who had spent years researching and planning potential attacks on MPs, had defended his actions by saying Mr Amess deserved to die as a result of voting for airstrikes on Syria in 2014 and 2015.
Ali, a London man with Somali heritage, had denied charges of murder and preparing acts of terrorism.
Opening the trial, prosecutor Tom Little said the case was “nothing less than an assassination” carried out because of a “warped and twisted and violent ideology.”
“It was a murder carried out by that young man who for many years had been planning just such an attack and who was, and is, a committed, fanatical, radicalised Islamist terrorist,” he said.
Mr Little said Ali bought the knife used to attack Mr Amess five years earlier, and that Ali tricked his way into meeting Mr Amess by pretending to be one of his constituents.
Mr Amess, 69, had been a member of Parliament since 1983. He was pronounced dead at the scene after the stabbing.
The prosecutor also said that Ali had researched and planned attacks on politicians and the Parliament building from at least 2019. The research included reconnaissance trips targeting work and home addresses of two other MPs, Mike Freer and Cabinet member Michael Gove, he added.
The slaying of Mr Amess shook the nation, as MPs often meet directly with the public. It came five years after Labour Party MP Jo Cox was shot and stabbed to death by a far-right extremist.