Police in the northwest suburbs say the two were found just after midnight Wednesday inside a unit at the Baldwin Greens Apartments on Green Lane North. They were transported to Advocate Lutheran General Hospital in Park Ridge, where they were pronounced dead.
Police say the 15-year-old had gang ties, and they had been called out to the address before. He was not enrolled in school, they said.
No arrests have been made.
Palatine police, the Major Case Assistance Team Forensic Unit and Cook County Medical Examiner's Office is investigating. They spent Wednesday going door-to-door talking to neighbors, even dumpster diving to find any leads in the case.
"It's calm in the mornings, during the day and afternoon," Javier Martinez said of the neighborhood. "Once it starts getting a little dark, a lot of people start coming out, and they just kind of hang out."
Martinez has lived in the area for a year. He said it's the first time he's seen anything like this.
"In this neighborhood, it's a gang. This whole complex is just one gang," Tracy Ramirez said.
Anyone with information should call police at (847) 359-9000 or the Crime Stoppers Tip Line at (847) 590-7867.