Officials said Park City police responded to the 300-block of Betty Street for a report of a person yelling and causing a disturbance in the road around 10 a.m. Saturday.
Responding officers found a visibly upset 29-year-old man, who told officers he killed his mother at their home, police said.
Officers entered the home and found the victim, who the Lake County Coroner's Office identified as 66-year-old Dorrie Gessler, unresponsive.
The Gurnee Fire Department transported Gessler to Advocate Condell Medical Center, where she was pronounced dead.
The coroner's office conducted an autopsy on Monday and found that Gessler died from strangulation.
Officers took the victim's son into custody. He has been charged with first-degree murder.
The 29-year-old is being held in custody pending his first court appearance on Monday.
Officials did not immediately provide further information.