An Illinois man pleaded guilty Monday to killing seven people and injuring dozens more when he opened fire on a 2022 Independence Day parade in a Chicago suburb, a stunning development moments before opening arguments in his trial on charges of murder and attempted murder.

Appearing in a Lake County circuit courtroom, Robert E. Crimo III, 23, withdrew his earlier not-guilty plea in the Highland Park shooting.

Prosecutors initially charged him with 21 counts of first-degree murder — three counts for each person killed — as well as 48 counts of attempted murder. Prosecutors dropped the less serious 48 counts of aggravated battery before the start of the trial with jury selection last week.

On Monday, Judge Victoria Rossetti read the charges to Crimo and asked questions to be sure he understood before any open plea was read to the court. He was sitting next to his lawyers wearing a dark suit.

“Is that what you went over with your attorneys?” Rossetti asked.

“Yes,” Crimo replied to the judge.

He gave one-word answers, indicating he understood the charges. His mother, Denise Pesina, had a brief outburst at the news and was called up to the judge for a warning.

“We’re going to move forward. You are not a party to this proceeding. If you would like to stay in the courtroom please have a seat and be quiet,” the judge said to her.

She was allowed to stay.

The judge said with the plea change, there would be no trial or further motions on the case.

“He has knowingly and voluntarily waived those rights and pleaded guilty,” Rossetti said.

Lake County prosecutors read the names of all those killed in the shooting and of those injured in the shooting, with the judge stopping to ask questions to make sure Crimo understood.

They went over the substantial evidence, including his prints on the gun used in the crime, and statements to police admitting to the mass shooting.

Sentencing will come April 23, but Crimo is certain to spend the rest of his life behind bars. Each count of first-degree murder carries a natural life prison sentence.

Crimo did not further address the court or ask questions before leaving the courtroom.

His defense attorneys declined comment ahead of the trial.

Security was very tight for the proceedings at the courthouse in Lake County, with multiple bag checks and observers required to lock up their phones. The crowd at what was supposed to be opening statements included survivors and their family members.

Jurors, who were chosen last week, had not even been let into the courtroom yet when the plea change happened.

The trial that began Feb. 24 was expected to last about a month with testimony from survivors and police. Prosecutors had submitted thousands of pages of evidence, as well as hours of a videotaped interrogation during which police say Crimo confessed to the shooting. But the 24-year-old had then pleaded not guilty.

Dozens of people were wounded in the shooting in the suburb about 50 kilometers (30 miles) north of Chicago. The wounded ranged in age from their 80s down to an 8-year-old boy who was left partially paralyzed.

Witnesses described confusion as the shots began, followed by panic as families fled the downtown parade route, leaving behind lawn chairs and strollers to find safety inside nearby businesses or homes.

Authorities said Crimo perched on a roof and fired into crowds assembled for the annual Fourth of July parade in downtown Highland Park.

The criminal case proceeded slowly for months, partly due to Crimo’s unpredictable behavior. In June 2024, when he was expected to accept a plea deal and give victims and relatives a chance to address him publicly, Crimo showed up to court in a wheelchair and rejected the deal, surprising even his lawyers.

He also fired his public defenders and said he would represent himself. Then he abruptly reversed himself.

As potential jurors were questioned last week, he sporadically appeared in court, at times refusing to leave his jail cell.

Father charged, tried earlier

The trial came almost two years after his father’s case focusing on how Crimo obtained a gun license.

In 2019, at age 19, Crimo was only allowed to apply for a gun license with the sponsorship of a parent or guardian. His father agreed, even though a relative had reported to police that his son had a collection of knives and had threatened to “kill everyone.”

His father, Robert Crimo Jr., a onetime mayoral candidate, was charged in connection with how his son obtained a gun license. He pleaded guilty in 2023 to seven misdemeanor counts of reckless conduct and served less than two months in jail.

He has attended his son’s hearings, sometimes making eye contact with him during court. He declined to discuss the case in detail ahead of the trial.

“As a parent, I love my son very much,” he said. “And Bobby loves this country more than anyone would ever know.”

Residents in the wealthy Highland Park community of roughly 30,000 set along Lake Michigan have mourned the losses deeply. Some potential jurors were excused because of their connections to the case.

The victims killed in the shooting included Katherine Goldstein, 64; Jacquelyn Sundheim, 63; Stephen Straus, 88; Nicolas Toledo-Zaragoza, 78; Eduardo Uvaldo, 69; and married couple Kevin McCarthy, 37, and Irina McCarthy, 35.

Survivors and their families have filed multiple lawsuits, including against the maker of the semiautomatic rifle used in the shooting and against authorities they accuse of negligence.