Orowo Omokoh, 28, was arrested on suspicion of conning Jette Jacobs, 67, after they met on an internet dating site. Photograph: Martin Rogers/Workbook Stock

Nigerian authorities have arrested a 28-year-old man suspected of defrauding an Australian widow in a fake online romance, a year after she was found dead during a trip to South Africa where she intended to meet him.

The Economic and Financial Crimes Commission (EFCC) said it had arrested Orowo Omokoh on 28 January on suspicion of conning 67-year-old Jette Jacobs out of $90,000 (£55,000) after they met on an internet dating site.

Jacobs, a grandmother, flew from her home in western Australia to meet Omokoh in South Africa last February, but died four days later under circumstances still being investigated by South African police. Omokoh had arrived in the country two days before her death.

An EFCC spokesman, Wilson Uwujaren, said: “We received a complaint about the fraudulent relationship from police in South Africa. We tracked him for a while, then we closed in.”

He stressed the Nigerian commission only had power to investigate the alleged fraud committed on its territory but would co-operate with South African police on any extradition request.

Fake online romances are a common form of advance fee fraud in Nigeria and are often called 419 scams, after the section in the penal code. Authorities say they have become more popular as the classic emails promising impossibly good business deals become less effective.