A right wing nationalist repeatedly said "Britain First" as he shot Labour MP Jo Cox three times and stabbed her in the street, the Old Bailey heard.
Thomas Mair, 53, ambushed the mother-of-two as she arrived for a regular surgery with her Batley and Spen constituents in June this year.
Prosecutor Richard Whittam QC told jurors Mair had planned the attack in advance and carried out the murder because of his "strong political and ideological interests".
Jurors at the Old Bailey were told Mair had researched the Ku Klux Klan, Nazis, serial killers and right wing politicians in the days prior to killing Ms Cox.
He had also used his local library to research Ms Cox, fellow Yorkshire MP William Hague, and Ian Gow, an MP murdered by the Provisional IRA.
A lot of people on the Eurosceptic right shamefully tried to make out this murder had nothing to do with politics. Politicians and the popular press have created a culture of fear and xenophobia, in which terrible incidents will happen again and again.