The Los Angeles County Coroner's Office confirmed the boy's death. An abuse investigation was launched earlier this week in Palmdale after deputies found the boy unconscious. Detectives say he may have been tortured.
The Los Angeles Sheriff's Department says the case is now being investigated as a homicide.
Authorities responded to an apartment on the 200 block of E Ave. Q-10 at 10:53 p.m. Wednesday and found the boy not breathing. The boy appeared to have been restrained at wrists and ankles, according to police.
The boy was airlifted to Children's Hospital Los Angeles in critical condition. He suffered from fractures to the head and had cigarette burns and cuts on his body.
"It appears the child has been struck numerous times about his body. He has a skull fracture. He has numerous broken ribs, and he also has burns to his body," said Sgt. Brian Hudson of the L.A. County victim's crime bureau.
The boy's mother, 29-year-old Pearl Fernandez, was booked for child abuse and child endangerment. Her boyfriend, 32-year-old Isauro Aguirre, was arrested and booked for attempted murder.
"The boyfriend made statements during his interviews, essentially he admitted to causing injuries to the child. The mother was aware that the assault was taking place and was actually present during portions of the assault on the child," Hudson said.
Detectives say the Department of Family and Children Services had been called to the apartment several times in the past. They would not elaborate as to why.
Neighbor Gwendolyn Boyd said she had been hearing banging coming from the apartment for the last two days.
Deputies say there were two younger siblings in the apartment as well, but it was unknown if they suffered any type of abuse.