Jestice James, 22, has been charged with two counts of murder and two counts of child abuse under circumstances or conditions likely to cause great bodily harm or death, according to the office of District Attorney George Gascón. She also faces two special allegations of child endangerment.
She faces life in prison if convicted of all charges. She's being held on $4 million bail.
One of the toddlers died Thursday after officers responded to a radio call of a child death investigation in the 20000 block of Sherman Way in Canoga Park, the Los Angeles Police Department said.
The boys' mother had "discovered them unresponsive," authorities said. Both children were taken to the hospital, where one of them died. The deceased boy was later identified as Josiah James by the Los Angeles County Department of Medical Examiner.
Mother arrested after 3-year-old son dies, twin brother critical: LAPD
Police on Monday confirmed that his brother Jestine died late Saturday.
A preliminary investigation indicated that the children "had ingested, or been exposed to, an unknown substance," police initially said. An official cause of death has not been released.
On Monday, Deputy District Attorney Jonathan Hatami identified the substance as fentanyl.
Their mother was arrested and booked on suspicion of murder and child cruelty.
Her expected court appearance Monday was postponed until Tuesday.
The boys lived at the Palm Vista Apartments, an affordable housing building run by the city of Los Angeles that includes some units for people experiencing homelessness.
The case is being investigated by the Police Department's Juvenile Division/Abused Child Unit.
Anyone with information about the case is urged to contact LAPD.