The two men were identified as Hong Kyq Kim, 53, and John Tae Kim, 83, according to the Cook County Medical Examiner's office. The men died of carbon monoxide poisoning, a Cook County Sheriff's Office official said late Friday.
Foul play is not suspected in the men's death. Autopsies on both men were inconclusive. It is undetermined when toxicology results will be completed.
Officers responded to a call of people in distress in the 9400-block of Harrison Street around 3:30 p.m. Thursday. They found two men dead - one in the basement and one on the second floor. One woman, the wife of John Tae Kim, was hospitalized in critical condition. The trio was discovered by the family's daughter.
PHOTOS: Deadly hazmat situation in Des Plaines
In addition, four Cook County sheriff's officers were also hospitalized after complaining of breathing problems. They were released late Thursday.
First responders used hazmat gear to enter the home. It's still unclear what fouled the air in the townhouse and what may have killed the men. A source said a car in the garage had its ignition on with a dead battery. There was apparently an empty slow cooker in the kitchen, where an unknown substance looked like it had burned away.
Both Hong Kyq Kim and John Tae Kim lived in the home for 14 years. The elder Kim suffered from a stroke and retired years ago, but he went back to work to run A-1 dry cleaners in suburban Wood Dale.
VIDEO: Friends said the family was valued members of Korean community
Earlier in the week, customers thought it was odd that they had not seen John Tae Kim. The store had not opened since Tuesday.
The Kim family attended the Chicago Covenant Presbyterian Church in Glenview, where fellow church members described the family as deeply religious.
"I feel lost," said Paul Kwak, a fellow church member. "Tragedy."
David Ser, a fellow church member, said John Tae Kim taught English as a second language at the church and called him a valuable member of the Korean community.
On Friday, church members stepped up to run the dry cleaners, while taking on the unfortunate job of informing customers about what had happened to the Kim family.
"He was just a wonderful guy," said customer George Anderson. "We'll miss him for sure."