The Illinois man accused of firing more than 70 rounds at Independence Day paradegoers in Highland Park, Illinois, Monday dressed up in a woman's clothing in an alleged effort to conceal himself, according to investigators.
Robert E. Crimo III, 21, dropped the weapon at the scene and blended in with the crowd to flee, according to Chief Deputy Chris Covelli, of the Lake County Major Crime Task Force. Authorities had initially reported his age as 22, but they issued a correction Tuesday.
He allegedly used a "high-powered rifle" to kill six out of more than 30 shot, Covelli told reporters during a Tuesday morning news briefing. He said there was no evidence anyone else was involved in the massacre.
But Crimo allegedly preplanned the attack for weeks, he said, and blended in with the crowd as he walked to his mother's house before escaping in her car. Authorities recovered a second rifle in his mother's silver Honda Fit vehicle upon Crimo's capture in North Chicago. He purchased the weapons locally from an unspecified seller.
"Crimo preplanned this attack for several weeks," Covelli said. "He brought a high-powered rifle to this parade. He accessed the roof of a business via a fire escape ladder and began opening fire on the innocent Independence Day paradegoers."
Law enforcement sources told Fox News Digital that in addition to an AR-15-style rifle used in the attack, Crimo had also legally purchased a bolt-action rifle, a handgun and a shotgun. Covelli said he may have owned multiple pistols.
Authorities are asking anyone with information, video or images from Monday's parade to contact police or the FBI as investigators build their case. Charges were still under review Tuesday, police said.
The attack began around 10:14 a.m. CT at the intersection of Central Avenue and Second Street. The parade began at 10 around at the corner at Laurel and St. Johns Avenues and would have concluded at Sunset Park.
Police said five victims were found dead at the scene, and a sixth succumbed to injuries at the hospital.
Crimo is a self-described rapper using the pseudonym "Awake." He has a history of posting disturbing images online, including graphics depicting shooting violence.
Covelli said Tuesday that police had not yet identified a motive in the attack.
The suspect's uncle, Paul Crimo, told FOX 32 Chicago that he saw "no warning signs" and that his nephew was a quiet young man.
"He keeps everything to himself, and he doesn't express himself," he told the station. "So he just sits down on his computer. There's no interaction between me and him."