In Scottsdale, Arizona, where Kirk lived with his wife and two young children, several dozen gathered at a park on the evening of Sept. 10 for a rosary vigil honoring the murdered activist, an evangelical Christian whose wife, Erika, has been described in media reports as Catholic.

US President Donald Trump said on Friday “with a high degree of certainty” that the suspect in Charlie Kirk killing has been caught, adding that someone “very close to him turned him in.”

Kirk, who began as a teenage conservative campus activist before rising to prominence as a leading podcaster and a trusted ally of Trump, was shot dead on Thursday during one of his signature public ...