The Ada County Sheriff's Office says that Friday morning emergency crews responded to a home in the 5000 block of South Staaten Place in Boise for a report of a baby that had fallen out of an infant bouncy seat and was not responding.
Paramedics took the baby to St Luke's Hospital with significant life-threatening injuries to his head and body.
The baby died Saturday morning from his injuries.
Investigators say they determined the infant's injuries were not consistent with a fall, but were caused by the child's father, Reynaldo "Lucas" Sanchez, 19.
A judge issued a $1 million warrant for Sanchez's arrest Friday evening, and he was booked into the Ada County Jail about 6:15 p.m.
The sheriff's office says Sanchez was alone with the child at the time of the incident.
The case is still under investigation, and a new charge is expected by Monday.