A 21-year-old man accused of shooting into a crowd watching a Chicago-area Independence Day parade was indicted by a grand jury on 117 counts, including 21 counts of first-degree murder, the state's attorney's office has said.
The suspect, Robert Crimo, has been held without bail since he was arrested after the shooting at the July Fourth celebration in Highland Park that left seven people dead and more than three dozen injured.
He is set to appear in court on 3 August for his arraignment, Lake County State's Attorney's Office said.
Under the US legal system, a prosecutor can convene a panel of citizens, or grand jury, that has the power to decide whether there is sufficient evidence to bring a defendant to trial.
If convicted on the murder charges, Mr Crimo would face a mandatory sentence of life in prison without the possibility of parole, Eric Reinhart, the state's attorney for Lake County, said the day after the shooting.
The bloodshed was part of a recent flare-up of mass shootings that have renewed debate about gun violence in the United States.
It followed an attack in Uvalde, Texas, that left 19 school children and two teachers dead and a shooting at a supermarket in Buffalo, New York, that killed ten people.
In Highland Park, prosecutors said Mr Crimo had planned the attack for weeks before climbing to a rooftop and firing more than 70 rounds at parade spectators.
He then made his getaway dressed in women's clothing and makeup to cover his facial tattoos, they said.
The Smith & Wesson semiautomatic rifle, similar to an AR-15,used in the shooting was found at the scene, and the suspect had a similar weapon in his mother's car, which he was driving when he was arrested, according to county prosecutors.
Police said they had no immediate evidence of any anti-Semitic or racist basis for the attack.
The area has a large Jewish community. Investigators were reviewing videos Mr Crimo had posted on social media containing violent imagery.
A spokesperson for the Lake County Sheriff's office said Mr Crimo legally purchased five guns in all, rifles and pistols, despite having come to law enforcement's attention on two prior occasions for alleged behavior suggesting he might harm himself or others.
