A detainee set fire to a mattress inside a cell on Tier 5A of Cook County Jail's Residential Treatment Unit around 3 p.m. Sunday, sending thick smoke through the fifth floor and sending 10 correctional officers to the hospital for smoke inhalation. The inmate was also treated and released, along with the officers, before being returned to custody the same day.
According to the ABC7 Chicago, the fire was quickly extinguished, but the smoke forced deputies to evacuate Tier 5A along with all adjacent tiers on the fifth floor. As reported by CBS Chicago, Tier 5A is part of the Residential Treatment Unit.
A Tier With a Troubled Recent History
In November 2025, 24-year-old detainee Martinez Duncan died after a fire broke out inside his locked cell in the Residential Treatment Unit, according to Hoodline, a case Hoodline previously covered in a detainee's death after cell fire.
A preliminary finding in the Duncan fire was that it involved a lit wick made from tightly wound toilet paper, commonly used to smoke illegal drugs.
Inside a Specialized but High-Risk Facility
The Residential Treatment Unit is designed to serve individuals with elevated mental health and medical needs.
The Fire's Impact
The fire sent 10 correctional officers to the hospital for smoke inhalation.
Security Gaps Under Scrutiny
The fire also arrives amid broader questions about how Cook County Jail is equipped to handle cell emergencies. An Illinois Answers Project investigation published September 15 found that Cook County Jail does not use pepperball launchers for inmate or riot control, unlike 20 other county jails across Illinois that maintain the high-pressure chemical launchers, according to reporting from NPR Illinois.
Hoodline has previously reported on contraband-related fire wicks at the jail. Sunday's fire sent 10 correctional officers and the detainee for treatment, underscoring the risks posed by fires in the unit.
