Upon changing his plea to guilty Monday, the Highland Park parade shooter signed "Donald Trump" rather than his own name on a trial waiver document, CBS News Chicago has confirmed. The document acknowledges that a defendant has given up his right to a trial upon pleading guilty.

Opening statements begin Monday in the trial of Robert Crimo III, who is accused of opening fire at a Fourth of July parade in the affluent Chicago suburb of Highland Park.

Shooter Robert Crimo III changed his plea to guilty in the July 4, 2022, mass shooting just before opening statements were about to start in his trial. Marissa Sulek reports.

The shooter pleaded guilty to all 21 counts of first-degree murder and 48 counts of attempted murder. He was accused of killing seven people and wounding dozens more at Highland Park's Fourth of July parade in 2022.