The American rock band Chicago is mourning the passing of founding member Walter Parazaider, who died on Wednesday (June 18) following a battle with Alzheimer’s disease.

The group shared a message via social media expressing their heartbreak at the sad news and extending their condolences to Parazaider's family, friends, and fans.

Parazaider was instrumental in bringing Chicago together as a band and booking their early shows.

His contributions to the band were invaluable, and his greatest gift was reportedly bringing people together through music.

Parazaider was diagnosed with Alzheimer’s six years ago and passed away surrounded by his wife JacLynn at 2:10 AM Wednesday morning.

Parazaider had been married to JacLynn for 59 years, and she reflected on their time together in a statement shared via TMZ.

Chicago fans around the world are mourning Parazaider's loss as they remember his legacy through the band’s music.