The man responsible for shooting and killing seven people during a Fourth of July parade in Highland Park, Ill., in 2022 pleaded guilty to all charges on Monday before opening statements in his trial could begin.

Robert Crimo III, 24, unexpectedly changed his plea, causing the judge to question the defendant on whether he was sure about the decision that he was making. He pleaded guilty to all 21 charges of first-degree murder, three counts for each person killed, in addition to 48 charges for injuring dozens more.

Crimo previously pleaded not guilty and rejected a plea deal last year.

In July 2022, the shooter fired roughly 80 rounds into the parade crowd using a semi-automatic rifle. He dressed himself as a woman to conceal his identity before accessing a rooftop to open fire on parade attendees.

Crimo then fled the scene in Highland Park, a city north of Chicago, and drove around Madison, Wis., where he contemplated another mass shooting. Authorities apprehended the suspect about eight hours after the Highland Park attack. DNA evidence was found on a rifle near the scene of the shooting, to which he confessed upon his arrest.

At the time, Crimo left disturbing content on his social media profiles, which contained music videos depicting mass murder.

Prosecutors described the shooting as a “premeditated and calculated attack,” although a definitive motive remains unclear. They revisited the factual events of that day during Monday’s hearing before the judge.

Almost all 48 survivors of the shooting were planning to testify until the defendant changed his plea, thereby canceling the planned jury trial.

The seven deceased victim were Jacquelyn Sundheim, 63; Nicolas Toledo-Zargoza, 78; Irina McCarthy, 35; Kevin McCarthy, 37; Katherine Goldstein, 64; Stephen Straus, 88; and Eduardo Uvaldo, 69.

Nearly three years after the mass casualty event, the judge set his sentencing date for April 23. Crimo will be sentenced for the rest of his life in prison without eligibility for parole.