Ericka Gallego is accused of breaking into her son's home in Contra Costa County last month and snatching her 4-month-old granddaughter from her crib.
Prosecutors say Gallego then took a taxi back to her house in El Monte -- in Southern California -- and tried to pass-off the baby as her own.
El Monte police arrested Gallego and the baby is fine. Gallego remains in custody.
