Kasanga, who had developmental disabilities and a swallowing disorder, lived for 12 years at a Community Integrated Living Arrangement, or CILA, in Rolling Meadows.
It serves adults with developmental disabilities.
Ashley Kasanga said her sister's loss has devastated their close-knit family.
"She brought love to every room she stepped in. She has the biggest heart. She smiled every day," she said.
According to the family's attorney, Margaret Battersby Black, Clearbrook had agreed to a care plan requiring staff to supervise Kasanga during meals because of her high risk of choking.
Black said that on April 25, Kasanga was left alone while eating.
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"Emily was given her lunch and allowed to eat it unsupervised in the living room, while the one staff member attending to those residents was busy elsewhere," she said.
A civil lawsuit filed by the family states that when the staff member returned, Kasanga was choking. Black said the staff member then "instructed other disabled residents to provide the Heimlich maneuver instead of herself and those residents obviously did not have any medical training."
Kasanga was pronounced dead at the scene. Hours later, her brother arrived for a planned visit, but the family says they had not been told she had died.
Her aunt, Helen Sichinga, said she contacted the Illinois Department of Public Health overnight.
"I personally called IDPH at 3 a.m. in the morning to see if we can get some answers. IDPH was shocked because in a period of over 10 hours, nobody had reported anything," she said.
The lawsuit names both Clearbrook and the staff member. The case comes as the U.S. Department of Justice continues investigating Illinois community-based services, including CILAs.
Kasanga's family says they hope the case leads to stronger protections for people living in Illinois group homes.
Clearbrook has not responded to a request for comment.