Washington DC - A 24-year-old man accused of firing from a rooftop on an Independence Day parade, killing seven people and injuring 48, pleaded guilty on Monday just minutes before opening arguments were set to begin in his trial.

Robert Crimo III was charged with murder, attempted murder, and dozens of other counts for the violent attack on a July 4, 2022 parade in the affluent Chicago suburb of Highland Park.

Jury selection was completed last week and opening arguments in Crimo's trial were scheduled to begin on Monday at the Lake County Courthouse in Waukegan, Illinois.

But Crimo changed his plea to guilty just moments before they began.

Sentencing was set for April 23. Crimo faces a sentence of life in prison without parole.

According to prosecutors, Crimo climbed onto a rooftop overlooking the parade route armed with a semi-automatic rifle and emptied three 30-round magazines into the crowd before fleeing.

Crimo was allegedly disguised in women's clothing and had used makeup to conceal several distinctive facial tattoos, including the word "Awake" above his left eyebrow and the number "47" on his temple.

He was captured about eight hours later following a car chase.

Crimo's father, Robert Crimo Jr, pleaded guilty in November 2023 to reckless conduct for helping his son obtain the assault rifle used in the shooting, a rare case in which a parent was held criminally responsible for the actions of their child.

Crimo Jr, who owned a delicatessen in Highland Park and once ran for mayor, pleaded guilty to seven misdemeanor counts for helping his son obtain a state firearms permit even though he knew he had a history of mental illness.

He was sentenced to 60 days in jail.