Former U.S. Senator Jon Kyl of Arizona died Thursday at the age of 84. His family announced the death, stating that he succumbed to complications from a neurological disease.

Kyl had stepped back from public life in December 2025 after revealing a diagnosis of a neurological condition that manifested as dementia. In a statement at the time, he expressed gratitude for his family and his service to Arizona and the nation.

A Republican known for his conservative principles and command of policy details, Kyl represented Arizona in the U.S. House from 1987 to 1995 and in the Senate from 1995 to 2013. He served as Senate minority whip from 2007 until his initial retirement. In 2018, he was appointed by then-Governor Doug Ducey to temporarily fill the Senate seat left vacant by the death of Sen. John McCain.

Arizona Senate Republicans issued a statement mourning the loss, describing Kyl as one of the state's finest statesmen who combined conservative conviction with deep respect for public service. Former Gov. Ducey praised Kyl's principled leadership and mentorship.

Kyl was born in Nebraska in 1942 and earned his law degree from the University of Arizona. He built a career as an attorney in Phoenix before entering Congress. After leaving the Senate in 2013, he worked as a lobbyist.

Memorial services are to be announced at a later time. Kyl is survived by his wife, Caryll, and their family.