A relative called police to the home in the 6400 block of West 83rd Place in Burbank about 9:30 a.m. Wednesday, according to Burbank police.
The victims -- identified by the Cook County Medical Examiner's office as 79-year-old Peter Mountain and 80-year-old Sally Lopez -- were found unresponsive in a bedroom, police said.
Autopsies performed Thursday found Mountain died of multiple gunshot wounds and an incise wound to the neck; Lopez suffered multiple gunshot wounds, incise wounds, and a blunt force trauma injury to the head, the medical examiner's office said. Both deaths were ruled homicides.
Officers found no sign of forced entry to the home, and authorities said they did not believe the attack was a random act of violence and burglary or robbery was not a motive.
"Our thoughts and prayers go out to the Lopez family as they leave behind several children," police said in a statement.
Burbank police and the South Suburban Major Crimes Task Force have more than 40 investigators working the case and "using every investigative tool available."
(Source: Sun-Times Media Wire - Copyright Chicago Sun-Times 2013.)