Kevin Hadley is a former firefighter that was assigned to Rescue Squad 3, and he was transferred out after a few incidents occurred between him and Peter Mills.

Hadley took the forced transfer personally, and began to target Peter Mills and Kelly Severide, his former lieutenant. Hadley started fires at particularly difficult buildings that were listed on the "dangerous buildings" list. This lead to an investigation by the Chicago Police Department and the CFD Fire Investigations Unit.

Kevin Hadley was eventually arrested and found guilty of arson.

He is now serving his sentence in prison.