The Orange County sheriff's office says it is unclear whether Elizabeth Fontaine, a Texas attorney, or her mother Bonnie Hoult was responsible for the shootings Monday in an upscale home in San Clemente.
Both were found dead along with 4-year-old Catherine and 2-year-old Julia after Fontaine failed to show up for a custody hearing.
Sheriff's spokesman Jim Amormino says investigators found a handgun between the women's bodies and will examine any DNA evidence on the weapon to identify the killer.
A judge had gave temporary custody of the children to Fontaine's sister.
