Los Angeles (CNN) -- A 7-month-old boy who authorities say was pushed by his mother from the fourth story of a parking garage died Wednesday, and his mother has been charged with murder, according to the Orange County, California, district attorney's office.
Sonia Hermosillo, 31, of La Habra, California, was arrested Monday soon after her baby fell from the parking garage at Children's Hospital of Orange County.
The baby had medical conditions that required regular treatment at the children's hospital, the district attorney's statement said, and he wore a helmet for one of his medical conditions.
"Hermosillo is accused of removing the victim's helmet and pushing her baby from the parking structure with the intention of murdering him with the four-story fall," the statement said. "Hermosillo is accused of then walking inside the hospital, validating her parking, and fleeing the scene."
"Baby Noe," as the district attorney's statement referred to the infant, was critically injured and died Wednesday at the University of California-Irvine Medical Center.
A witness saw the baby fall and called police. Investigators interviewed several witnesses and reviewed a surveillance video from the garage.
The image of a license plate on a 2000 Chevy Blazer seen leaving the garage shortly after the incident led police to Hermosillo. Authorities found an empty child seat in Hermosillo's vehicle, according to a police statement.
While police were investigating, Hermosillo's husband called the La Habra police department and reported his wife and the baby missing, authorities said.
Hermosillo, who was initially charged with attempted murder, was being held Wednesday on $1 million bail on new charges of one felony count of murder and one felony count of assault on a child with force likely to produce great bodily injury resulting in death.
If convicted, she faces a maximum sentence of 25 years to life in state prison, according to the district attorney's office.
Hermosillo was scheduled for arraignment on the new charges on Thursday.
The district attorney's statement said Hermosillo has two other children.
CNN's Jillian Ohlenschlaeger contributed to this report.