ABC7 is concealing the two men's identities because they have not yet been charged.
The brothers' home is now boarded up, though a spectacle remains outside. People drove by to take photos, and white tents dotted the property as police continued searching for answers.
"It's a very sad situation," said Lyons Police Chief Thomas Herion.
Police responded to a home in the 3900-block of Center Avenue earlier this week. Two brothers, aged 45 and 41, live there. One of them allegedly told police his mother and sister were buried in the backyard after dying in 2015 and 2019, respectively. The brothers told police they had died from illness.
WATCH: Lyons police give update after digging for bodies in backyard
Police confirmed they had recovered bodies in the backyard Saturday. The bodies have not yet been identified, but investigators said they will use DNA to see if the remains are in fact the brothers' biological relatives.
In a press conference Saturday afternoon, Herion said the bodies' conditions is consistent with deaths in 2015 and 2019. Autopsies are expected to be performed Sunday, police said.
While charges have not officially been filed, that could change once an autopsy is complete. Concealment of a death is a class 4 felony in Illinois.
The investigation into the home began when the water company alerted police that water hadn't been used at the home for years. Gas and electric use had also been minimal.
Upon arriving, police found a severe case of hoarding. The home contained jars filled with urine and piles of possessions throughout the two-story home, as well as multiple cats and dogs running around the property.
"It was multiple liters of urine," Herion said. "There was no running toilets. Every room, the front door, the backdoor were completely barricaded with debris, boxes."
Several animals were also taken in by the Humane Society, police said Saturday.
Some neighbors said they always thought the brothers, who pretty much kept to themselves, were a little odd.
"We've known something going on for some time," said neighbor Brian King. "I feel sorry for the people because there's been, if you want to say, medical issues for the boys."
"It's just surreal," added fellow neighbor Marth Castaneda.
The brothers told police their mom, who was in her late 70s, was pushed down the stairs by their sister in December 2015 and died sometime the following week from her head injury. The brothers then said their 42-year-old sisters got sick and died in 2019.
"Where are they? He indicated they were buried in the back yard, he said, 'Oh they got sick, they died and we just buried them in the backyard,'" Herion said.
The state of Illinois has no record of their deaths. Police said all evidence points to the bodies being in the yard.
The brothers also allegedly told police their father had died in 2012 and they had cremated him.
"She was a hard-working lady and took care of three kids," King said about the men's mother, who police say would be about 79 years old today.
The brothers were then taken in for a mental evaluation last week, police said, and were released within about two hours.
"They were evaluated mentally, physically, psychologically, [and] they were subsequently released from MacNeal hospital," Herion said.
The city had been paying for them to stay in a hotel as the investigation continues.
The house is said to be in such deplorable conditions that the men were allegedly going in and out of windows because the home's doors were unusable.
"I just hope they get the help they need, obviously there's something that's not correct," Castaneda said.
Police said they brought in extra help, including an archeologist, for the extremely tedious task of emptying the home and looking for any evidence of what happened inside and sifting dirt in the yard outside.
"We are going to have to have expert crews come in to empty this residence," Chief Herion said. "We will have detectives outside as items are coming out of the house every piece of evidence is going to have to be evaluated read and determine whether it's valuable or not valuable."
Police said they are currently treating this as a homicide investigation, but cautioned the brothers could be telling the truth about how their relatives died.