Washington: For some Americans on the far right, Charlie Kirk died a "martyr" - and any criticism of the hugely popular conservative activist must be punished. Online vitriol and grassroots persecution have exploded in the wake of the 31-year-old's assassination, deepening already fraught political divisions.

Laura Sosh-Lightsy, an assistant dean of students at a Tennessee university, quickly landed in hot water after posting about Kirk's death: "Hate begets hate. ZERO sympathy," she wrote on Facebook.

Republican Senator Marsha Blackburn condemned the remark, demanding Sosh-Lightsy's removal. That same night, Middle Tennessee State University's president announced an employee had been fired for a "callous" comment about Kirk.

Kirk, who mobilized millions of followers in support of Donald Trump's bid for a second term, was both revered and reviled for his pro-gun, anti-abortion and anti-immigrant rhetoric.

Police say shooting suspect Tyler Robinson, arrested Thursday, engraved anti-fascist slogans on his bullet casings - fuelling claims from the right that he was a "far-left" killer.Trump, who hailed Kirk as a "giant of his generation," has led efforts to memorialize him, with senior officials cracking down on his critics.

Defence Secretary Pete Hegseth has ordered military personnel to identify colleagues mocking Kirk's death, while Under Secretary of State Christopher Landau warned that foreigners praising the killing would face visa consequences.

Far-right conspiracy theorist Laura Loomer has been among the most aggressive in targeting detractors. She exposed a FEMA employee who slammed the decision to lower flags for "the literal racist homophobe misogynist." The staffer has since been placed on leave.