John Kezdy, the singer for the Chicago punk rock band the Effigies and longtime prosecutor with the Illinois state’s attorney’s office, died Saturday, three days after he was riding his bicycle in north suburban Glencoe and struck an Amazon van that was stopped along a roadway.

Mr. Kezdy, an avid cyclist who lived in Highland Park, was pedaling along Sheridan Road Wednesday in the intense afternoon heat of last week’s heat wave when he slammed into the back of the delivery van, which was stopped with its hazard lights flashing, according to Glencoe Deputy Police Chief Andrew Perley.

It’s unclear why Mr. Kezdy, who had a clear line of sight and continued pedaling to the point of impact, didn’t brake or swerve to avoid the van, said Perley, who added that investigators have video showing the accident. 

Mr. Kezdy, who was transported to Evanston Hospital in critical condition, was 64.

No citations have been issued. Perley said heat may have played a factor.

Mr. Kezdy, a graduate of Evanston Township High School, formed the Effigies in 1980 after dropping out of the University of Wisconsin. They played Chicago clubs and toured the United States in a van. The Effigies recorded three albums of original songs, including “Body Bag,” while making a name for themselves between 1980 and 1986, when the band broke up.

The group earned a measure of fame as they played alongside bands including Hüsker Dü, Black Flag, Dead Kennedys, Toy Dolls and Naked Raygun, a band that Mr. Kezdy’s late brother, Pierre Kezdy, was in.

The Effigies even opened for Run-DMC once at the Vic Theatre.

But they never had the sort of commercial success that allowed them to quit their day jobs, band member Paul Zamost said.

Mr. Kezdy finished college, earned a law degree from Northwestern University and became a prosecutor. 

The group got back together in the late ’90s for reunion shows and again in the 2000s, and decided to give it another shot in 2021, according to Zamost.

The band was putting the finishing touches on a new album and was scheduled to rehearse the evening Mr. Kezdy was fatally injured.

The group hoped to shake the rust off and begin playing gigs again, and perhaps fulfill a bucket-list dream of touring Europe, Zamost said.

Mr. Kezdy came up with the title of their unreleased album: “Swift Severe and Sure”

“That was John being a lawyer, that’s how he wanted justice to be. It’s kind of ironic that’s the way he went out,” Zamost said.

Kezdy ran the statewide grand jury bureau of the Illinois attorney general’s office before he retired last year.

“I played in a band with probably the only lead singer who put someone in jail,” Zamost said.

Mr. Kezdy was at the Independence Day Parade in Highland Park last year when a gunman opened fire, killing seven people. 

Mr. Kezdy suffered a graze wound to his arm, and his wife suffered a shrapnel wound.

Mr. Kezdy and his longtime friend, drummer Steve Economou, were hanging out at Neo in 1979, a nightclub that was the center of the city’s punk scene, when they met Zamost, a bass player.

“We were just kind of hanging out when John and Steve came by with leather jackets,” Zamost said with a laugh. “John always sort of had an attitude and I was like, ‘There’s a good guy to be in a band with. He’s got a bad attitude.’ ”

Though punk rock had an anti-authority message at its core and many of its icons died from drug abuse, Kezdy saw no conflict between playing it and representing the state in criminal cases.

“I’ve never seen punk rock as being synonymous with breaking the law. To me, the basic things that I admire in punk rock, they end up being kind of old conservative values: independence, complete self-reliance,” he told the Sun-Times in story that was published in 2007.

Former Sun-Times music critic Jim DeRogatis wrote in 1999 that the Effigies made a significant mark on the punk scene.

“Punk rock emerged in the late ’70s as a reaction against right-wing politics, and as a musical alternative to the bloated, soulless sounds that had come to dominate the pop charts. By the mid-’80s, a second generation of Midwestern punks was introducing a new sophistication to the music while continuing to voice their anger at the status quo.

“Leading the charge in Chicago: Naked Raygun, the Effigies and Big Black. ... The ground that Naked Raygun and the Effigies broke would help pave the way for the alternative explosion of the mid-’90s, which saw homegrown talents such as the Smashing Pumpkins, Urge Overkill, Liz Phair and Veruca Salt win major national success.”

Kezdy found his love for punk rock after hearing the Sex Pistols’ “Never Mind the Bollocks, Here’s the Sex Pistols.”

“That album changed my life,” Kezdy told the Sun-Times. “It wasn’t just the music. It was the whole attitude.”

Funeral services are being arranged.