Naperville police were investigating what they termed a suspicious death of a man found Wednesday morning inside a townhouse on Vail Court in the city's Estes Park neighborhood.
Police said there was a strong smell of natural gas when they arrived, but they were uncertain what role, if any, it may have played in the man's death.
Authorities said they are not releasing the man's name pending notification of his next of kin. They said an autopsy will be performed and more information likely will be available Thursday.
A neighbor, Melody Mondello, said the man's garage door had been open since Monday and a garbage bin he normally would have brought in was left unattended outside his townhouse.
Police remained on the scene Wednesday night and said their investigation is continuing.