Five social escorts in Singapore disappeared from the face of the Earth 40 years ago in an incident that remains unsolved till this day.

However, interest in the case has been reignited in recent times, as the abduction is believed to have been carried out by a rogue nation still making the news often these days.

What happened?

The five young women were reported missing after supposedly attending a party on a cargo ship at the Eastern Anchorage on Sunday, Aug. 20, 1978.

A close friend of the women reported to the Marine Police on Monday night, after searching for them when they failed to return.

The five young women were aged between 19 and 24 at the time of their disappearance.

Four of them were Malaysians: Yeng Yoke Fun, 22, Yap Me Leng, 22, Seetoh Tai Thim, 19, Margaret Ong Guat Choo, 19.

The only Singaporean woman in the group was Diana Ng Kum Yim, 24.

They were taken to the cargo ship willingly by three foreigners, supposedly for a party on board.

What are some things that are known?

The Singaporean woman, Diana, first met the three men, believed at that time to be Japanese and Hong Konger sailors, two weeks before the women's disappearance.

The men were then introduced to the rest of the women by the Singaporean woman.

After meeting one another, the men invited the women to the party, promising them $100 an hour and a diamond ring each for their services.

The group's disappearance was reported to the authorities by Helen Tan, 22, who was a close friend of the women who went missing.

She recounted how she nearly accompanied them and almost became a victim herself: "I was asked to join them, but I turned them down because of an appointment at the race course."

Appeared legitimate

Based on media reports at that time, the five women were taken for a shopping spree on Saturday to prepare for the Sunday party.

They even went for a picnic with the sailors the next day before boarding the ship.

When the women did not return by Monday night, Tan got worried and searched for them.

She traced the group to Jardine Steps -- present day HarbourFront area -- with the help of a taxi driver at the hotel where the sailors were staying.

A boatmen said he ferried the group to the cargo ship, but when they went to the location where it was anchored, they could not find it.

Theories about what happened

Multiple theories have since been put forth about what could have happened.

But two theories have stood out: The women were believed to have been human-trafficked to enter the vice trade, or abducted by rogue nation, North Korea.

Traded to a prostitution ring

After the women went missing, the case was classified as kidnapping.

Up till today, no one knows what happened to them.

But one theory put forth by the media in 1978 was that there was a possibility the women were abducted by Hong Kong triads and traded to a prostitution ring in India.

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Abducted by North Korea

Another theory is that the men the women met were, in fact, North Korean agents posing as Hong Kongers and Japanese.

There has been deep suspicion brewing since 2017 that North Korean agents were behind the 1978 abduction, allegedly on orders from their supreme leader at that time.

This was following the murder of Kim Jong-nam in Malaysia at the hands of suspected North Korean agents in February 2017.

Tomoharu Ebihara, the director of the Association for the Rescue of North Korea Abductees (ARNKA) said the cold case that was 39 years old in 2017 should be opened again.

According to Ebihara, information on the possible existence of Malaysian abductees in North Korea was derived from various testimonies.

It is widely-believed that North Korea had been abducting citizens from multiple countries over the years, for various reasons, such as getting the foreigners to impart their knowledge of their home countries to the North Korean security department agents.

These testimonies were provided by South Korean actress Choi Eun-hee, and a former United States soldier, Charles Robert Jenkins.

Eun-hee herself was abducted in Hong Kong in 1978, while Jenkins deserted his unit and crossed into North Korea in 1965, and lived there until his release with his family in 2004.

Ebihara said: "According to Jenkins, he saw a picture of Yoke Fun (one of the women who disappeared in Singapore) and remembers meeting a similar woman at an amusement park in Pyongyang between 1980 and 1981."

Eun-hee, who had lived in Pyongyang until 1986, said she heard from a woman that a Malaysian couple lived in a separate residence in Pyongyang during her stay in North Korea's capital.

Suspicion of North Korean involvement

In 2005, a Japanese television station had produced on a special series trying to find out what had happened to these women.

It was during one interview then that the possibility of Malaysian women held in North Korea was raised.

One of those interviewed was the former American serviceman Charles Jenkins.

He said he had met a woman in Pyongyang, who had a striking resemblance to Yoke Fun.

The Japanese television station then contacted the Malaysian Chinese Association chief, Michael Chong, with the information.

Fast forward 10 years later in September 2015, a Japanese man appeared before the North Korea Human Rights Violations Council relating how he had not seen his mother since 1978 when she was abducted.

This was a separate incident that dealt with Japanese abductees -- a perennial issue that gets regular media airing.

Chong, the MCA chief, was once again informed about the case and that a United Nations special sitting on human rights had been convened in Geneva over this episode.

In other words, the case turned cold until the Jenkins disclosure in 2005, and has now come to light once again following the Geneva sitting in 2015.

While the focus at present is surrounding Japanese women believed to have been abducted, there is a possibility the Malaysians could be mentioned to be victims too.

Young women in Singapore solicited to join yacht parties these days:

Top photo via The Star, NLB eresources and NAS