The man accused of spraying gunfire into a July Fourth parade from a Chicago-area rooftop, turning a holiday celebration into a killing field, was due to make his first court appearance on Wednesday to face seven first-degree murder charges.

Authorities said on Tuesday that the 21-year-old suspect, Robert E. Crimo III, planned the attack for weeks before firing more than 70 rounds randomly into spectators before getting away dressed as a woman. Seven people were killed and more than three dozen were treated in hospital for gunshot wounds and other injuries after the carnage.