Authorities say two young Ohio girls and their mother were dead before a house explosion and fire that also killed their father.

Summit County's medical examiner said Thursday the girls were either strangled or smothered. Officials said the girls' mother died of a Prozac overdose and their father, 43-year-old Jeffrey Mather, died of burns after he set the fire using gasoline.

All four bodies were found inside the Northfield Center Township home on Jan. 11. The medical examiner found no evidence of smoke inhalation in the mother or daughters.

A medical examiner's investigator says it's unclear if 43-year-old Cynthia Mather killed herself or was poisoned. He says it couldn't be determined who killed 8-year-old Ruthie Mather and 12-year-old Alyson Mather.

Authorities have said Jeffrey Mather had told police he was depressed and suicidal when found in a car with shotgun in December.