The Las Vegas gunman sent his girlfriend abroad so she could not interfere with his deadly rampage, it has been claimed.
Marilou Danley, 62, was in the Philippines for some weeks before Stephen Paddock carried out the mass murder of 59 people on the Las Vegas Strip.
In an interview with Australia's Channel 7 TV network, Ms Danley's sisters said they were surprised to learn she had travelled to the Philippines.
One said: "I know that she don't know anything [about the killings]." Her sister is "a good person" who would have tried to stop Paddock, she said.
Another of the sisters, who live near Brisbane, Queensland, said they believed Ms Danley knew Paddock owned guns, but not as many as were uncovered by police in the Mandalay Bay hotel and at his home.
Ms Danley is now back in the US and investigators hope she will answer their questions about her partner's massacre of concert-goers on Monday.
Police had called her a "person of interest" but she is not thought to be under arrest.
Investigators are trying to discover why Paddock transferred $100,000 (£75,000) to the Philippines in the days before the massacre.
