Matthew Degner, of the 2800-block of Lombard in Berwyn, died of bronchopneumonia and the death was ruled natural, according to the Cook County Medical Examiner's Office. His body was found inside the home, which also contained more than 100 animals.
A spokesperson for Illinois Department of Family Services says that it is investigating allegations of neglect against the dead boy's mother and three siblings, ages 12 to 17, have been removed from the house.
A Yorkie Terrier mix is one of nearly 200 animals in the care of the Animal Welfare League. The group says they were found covered in feces and cockroaches.
"The animals are dehydrated, and they were in cages with dead animals," said Linda Estrada, Animal Welfare League. "Each cage had like four or five inches of mold and feces."
Police were initially called to the house Thursday after Degner was reported dead inside.
Neighbors say for years the home reeked of waste.
"I smelled feces, basically. It was horrible, nasty. It smelled like something was dying in there," said Jesse Catalan, neighbor. "I always used to assume that it was just manure for the plants the lady used to water every morning."
Neighbors say about a year ago, the family put up this green barrier on the front lawn and posted no trespassing signs.
"When I try to talk to them, they don't answer. If you say hi or something, they don't say nothing," said Rigoberto Cisneros, neighbor.
The Animal Welfare League says it found dozens of birds in the house as well as rabbits, gerbils, a guinea pig and two dogs. Also recovered were more than 100 cats, many of which are seriously ill and must be euthanized.
"There were 15 in one little cage. That was their life," said Estrada. "My heart weeps for the ones we can't save because they didn't do nothing wrong."