Mother, boyfriend charged with killing 4-year-old Chicago boy on his birthday

(CBS/WBBM) CHICAGO - A 28-year-old mother and her boyfriend were charged Sunday in the death of the woman's son on his fourth birthday.

Police say 34-year-old Cesar Ruiz was charged Friday with first-degree murder and concealing a homicide in the death of Christopher Valdez, CBS Chicago reports. The boy's mother, Crystal Valdez, was reportedly charged with endangering the life of a child and concealing a homicide.

Christopher died on his birthday Friday afternoon in what police described as a "possible domestic situation" at the child's home, CBS Chicago reports.

Although police have not yet revealed the details of the 4-year-old death, an autopsy on Saturday reportedly determined he died from multiple blunt force injuries and child abuse, according to the Cook County medical examiner's office.

Christopher's grandfather, Tom Valdez, said relatives arriving at the house to deliver a birthday cake, found the boy's body and called police, Fox News reports.

Police said the boy was dead when they arrived at the home Friday.