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

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

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."

According to multiple media reports, Motes issued a series of now-deleted tweets that illustrated she had a contentious relationship with her Academy Award nominated sister in the weeks leading up to her death. 

Back in Oct. 2013, Motes wrote about her family as she posted about her upcoming wedding: "It's a shame when you get more support from strangers than you do from your family. I can't wait to officially belong to another family!"

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