A seventy-five-year-old woman died after being engulfed in a horrific fireball after gardaí fear a large container of flammable liquid exploded in a friend's car. The revelation came as a 62-year-old man, who was rescued from a nearby river, was being questioned by detectives in a Cork garda station on suspicion of the unlawful killing of grandmother and mother-of-three Mary O'Keeffe. Central to the garda investigation is how the car fire started - and Mrs O'Keeffe's cause of death. One garda source said the SUV owner has insisted the tragic fire was accidental and may have been triggered by a cigarette.