Jack Bezner, 70, and his wife Susan, 64, were found stabbed to death in their Rosemead home in the 4200 block of Arica Avenue on Monday.
Detectives learned Lopez and the girl might be on their way to Texas in the Bezners' missing Nissan sport utility vehicle, and issued a multi-state bulletin listing the Nissan as wanted with armed and dangerous suspects aboard, said Capt. Michael Parker of the L.A. County Sheriff's Department.
Lopez has been booked on two counts of murder and auto theft. The girl is being held on auto theft charges.
City News Service contributed to this story.