WAUKEGAN, Ill (AP) — The trial of a suburban Chicago man accused of a mass shooting at a 2022 Independence Day parade that killed seven people and wounded dozens more is set to begin Monday.

Robert Crimo III faces 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 jury selection last week.

The road to the trial has been bumpy, with delays partly due to Crimo’s unpredictability, including his rejection of a plea deal that even surprised his attorneys. As potential jurors were questioned last week, he sporadically appeared in court, at times refusing to leave his jail cell.

Authorities alleged Crimo perched on a roof and fired into crowds assembled for the annual Fourth of July parade in downtown Highland Park, 30 miles (50 kilometers) north of Chicago.

Prosecutors have 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 has since pleaded not guilty.

His defense attorneys have declined comment ahead of the trial, which is expected to last about a month.

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.”

Prosecutors plan to call multiple law enforcement officers and survivors of the shooting to testify. They also will show videos of Crimo’s statements to police. Some of the videos already have been shown in court as prosecutors tried unsuccessfully to have them thrown out.

Crimo’s erratic behavior has contributed to court delays.

He fired his public defenders and said he would represent himself, then abruptly reversed himself. In June 2024, when he was expected to accept a plea deal and give victims and relatives a chance to address him publicly, he arrived at the court in a wheelchair and rejected the deal.

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.

City leaders canceled the usual parade in 2023, opting for a “community walk.” The parade was reinstated last year on a different route and with a memorial for the victims.

“Our community is once again reminded of the immense pain and trauma caused by the Highland Park shooting,” Highland Park Mayor Nancy Rotering said in a statement ahead of jury selection. “Our hearts remain with the victims, their families, and all those whose lives were forever changed by that devastating day.”

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.