The Tulare Police Department said they were notified by Valley Children's Hospital that the 2-year-old victim has died from his injuries.
All three suspects are now facing murder charges.
On Saturday, police received a call for an unresponsive 2-year-old boy with injuries consistent with abuse at Tulare Regional Medical Center. The toddler was brought in by a private vehicle, was not breathing and didn't have a heartbeat upon initial evaluation.
The boy's injuries were determined to be consistent with abuse, and investigators were called.
Investigators arrested Edward Dias, 36, Shania Alamillo, 23, and Adriana Alamillo, 27. All three were initially charged with attempted homicide, torture and cruel or inhuman corporal punishment of a child.
The child was stabilized at TRMC and then transported to Valley Children's Hospital.
Another child who also exhibited injuries consistent with abuse was found to be in the custody of the suspects, police said. That 3-year-old was taken into protective custody by Child Welfare Services.