The body of 67-year-old Jette Jacobs, from Wagin south of Perth, was found in a rented villa in Johannesburg on February 9.
Her money, credit cards, laptop computer and jewellery were missing.
She had travelled to South Africa to meet Jesse Omokoh, 28, whom she had met online and had sent more than $100,000 in recent years.
Police from WA's Fraud Squad say Ms Jacobs' children tried to talk her out of making the trip and warned her it would be a scam.
WA police are liaising with South African police to investigate the death.