Robert Crimo III, the Illinois man accused of opening fire at a 2022 Independence Day parade in Highland Park, pleaded guilty on March 3.

Experts say his guilty plea should stand. "He can sign Mickey Mouse or Donald Trump," said Richard Kling, a law professor at Kent College of Law. What matters, he said, is that there is a transcript of Crimo orally pleading guilty,

Robert Crimo III unexpectedly pleaded guilty Monday to all charges in the July 4, 2022, Highland Park parade shooting that killed seven people.

With the guilty plea, the trial was immediately called off. The jury was dismissed. The judge confirmed that Robert Crimo had voluntarily waived his right to a trial and accepted responsibility for all 69 counts, which included 21 counts of first-degree murder and 48 counts of attempted murder.

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.