The Los Angeles County coroner's office is investigating the death of Julia Roberts' 37-year-old half-sister.

Nancy Motes was found dead in a Los Angeles home Sunday while dog-sitting for a friend, said Lt. Larry Dietz. An autopsy has not been performed and there are no preliminary findings about how Motes died, said Dietz.

Motes is the younger sister of actors Julia and Eric Roberts.

People magazine reported the family released a statement that says Motes died of an "apparent drug overdose" but notes that no official cause of death has been determined. The statement describes the Roberts family as "shocked and devastated."

Roberts is nominated for an Academy Award for her role in August: Osage County.

An after-hours phone message left for Roberts' publicist was not immediately returned.