Patricia Lopez, of Holt, an unincorporated community seven miles west of Stockton, is being charged as an adult with first-degree murder and child abuse resulting in death after allegedly using a pair of scissors to kill the newborn, state media outlets reported.
The West High School student spent about five or six months concealing her pregnancy. Then, after giving birth prematurely in the bathroom of her family's home Monday, police say she killed the newborn girl.
According to the complaint, Lopez used scissors as a weapon, but it is unclear how the scissors were used.
Lopez did not tell her parents that she had given birth and buried the baby in a shallow grave near the family's single-wide trailer.
On Tuesday, Lopez showed up at a local hospital. Doctors examined her and determined she had recently given birth. This apparently led to questions about the newborn's whereabouts and condition. The hospital called the San Joaquin County Sheriff's Department at about 5 p.m.
Police questioned Lopez, then went to her home and found the infant's body buried in a nearby shallow grave. The baby is believed to be between 22 and 26 weeks of gestation, police said.
"The 17-year-old allegedly killed the baby inside the bathroom, put it in a plastic bag and buried it ... in a hole," sheriff's Deputy Les Garcia told ABC News 10 Sacramento.
Lopez was arrested early Wednesday and booked into juvenile hall.
Garcia told the newspaper that the baby's father, whom they are not identifying, has been contacted by investigators.
On Thursday, Lopez appeared in court before Judge Richard Giuliani. The charges were read against her, and the San Joaquin County District Attorney's Office announced it was charging her as an adult. A conviction could result in a sentence of 26 years to life.
The San Joaquin County Sheriff's Department referred inquiries about the case to the district attorney's office. Calls to the DA were not immediately returned today.
Deputy District Attorney Claire Van Vuren told reporters she is still waiting on the autopsy report. She declined to elaborate.
"We can't really speculate at this time what her motive was," Van Vuren said, according to The Stockton Record. "With the little information we have, we felt she should be tried as an adult."