Judge Tony Graf previously served as a prosecutor in Utah, including in the county where Mr. Kirk was shot and killed last year.

© Pool photo by Trent Nelson

The case against the defendant, Tyler Robinson, has played out since last September.

© Loren Elliott for The New York Times

A judge will determine whether there is enough evidence to go to trial. Mr. Kirk’s widow and parents are expected to be in court.

© Kevin Lamarque/Reuters

On Day 1 of what is expected to be a weeklong hearing, prosecutors played videos of the shooting for a judge, but they were graphic and kept from public view. Erika Kirk and Donald Trump Jr. were in court.

© Kevin Lamarque/Reuters