An autopsy conducted Wednesday shows Robert Grundei was shot in the back; authorities say he was killed by his brother after the two fought over living arrangements at the family's Sun City Huntley home.
Toxicology samples have been sent for analysis, according to a news release from the Kane County Coroner's Office.
Authorities said Grundei, 48, of Coral Springs, Florida, had been staying with his brother, Mark, 50, and mother, Alyce Grundei, at the home on the 11000 block of Morning Glory Lane. Robert was helping with its sale and with funeral arrangements after the death of a younger brother who drowned in Lake County earlier this month.
Mark Grundei suffered a head wound in the Memorial Day shooting and remains in critical condition in the intensive care unit at Advocate Sherman Hospital in Elgin Wednesday, Huntley Police Deputy Chief Michael Klunk said.
A bullet grazed Alyce Grundei's head while she was trying to break up the fight between her sons. The 81-year-old was treated and released from the hospital Monday night and is staying with family members in the area.
Klunk said it is unclear whether Mark Grundei shot himself after killing his brother. "We are waiting on the detectives to make a determination on that," he added.
Klunk told WBBM 780-AM it appeared Robert and Mark Grundei were fighting over who was going to live in their mother's house, even though it recently had been sold to a new owner. Mark and his mother already were living in the house. Klunk said Robert planned to move into his mother's house and have his older brother pushed out, and Mark was not happy about it.
Klunk said Wednesday a lot of the details are assumptions because police haven't yet interviewed Mark Grundei.
"We never talked to him on scene," Klunk said. "Both of them were unconscious on scene. We're working off theories. We're not going to have a definitive answer."
Police recovered a revolver from the scene but have not yet confirmed to whom the gun belonged.
Klunk said police detectives have consulted with the Kane County state's attorney's office, but charges against Mark Grundei have not been filed.