The man suspected of killing seven people and injuring dozens at an Independence Day parade in Chicago will face 117 charges.
Robert E Crimo III was arrested by police hours after shots were fired into the crowd during Fourth of July celebrations in the Chicago suburb of Highland Park.
More than 70 rounds were aimed at party families with a high-powered assault rifle.
The killer had dressed in women’s clothing to blend in and escape the scene.
The state attorney’s office has now confirmed that Crimo will be charged with 117 counts related to that day, including 21 counts of first-degree murder.
If convicted, he faces a mandatory life sentence without the possibility of parole.
The 21-year-old has been held without bail since his arrest.
Prosecutors allege Crimo planned the attack for weeks, before climbing onto a rooftop and shooting at parade goers on July 4.
The Smith & Wesson semi-automatic rifle, similar to an AR-15, used in the shooting was found at the scene.
It comes amid a series of mass shootings in the United States that have renewed the debate about gun violence in the country.
A shooting in Uvalde, Texas, left 19 schoolchildren and two teachers dead, and a racially motivated shooting at a supermarket in Buffalo, New York, killed 10 people.
Image: Image: AP
Investigators have reviewed a series of videos that Mr. Crimo had posted on social media that apparently contained violent images.
A spokesman for the local Lake County Sheriff’s Office said the suspect legally purchased a total of five handguns, rifles and handguns, despite having come to the attention of police on two previous occasions for alleged behavior that suggested that he could hurt himself or others.
Image: Vigil for the dead
Shortly after the attack on the parade, a statement released via Twitter by the parents of Mr. Crimo said his hearts went out to the victims.
“We are all mothers and fathers, sisters and brothers, and this is a terrible tragedy for many families, the victims, the marchers, the community and ours,” they said. “Our hearts, thoughts and prayers go out to everyone.”