Six people who died in a luxury hotel suite in Thailand were poisoned by drinks laced with cyanide, police have said.
Police suspect that one of the dead was behind the poisoning and was driven by crushing debt.
The six deceased were found dead by housekeepers at the Grand Hyatt Erawan hotel in the Thai capital Bangkok late on Tuesday.
Investigators believe they had been dead for 24 hours by then.
Two of the six had loaned “tens of millions of Thai baht” to another of the deceased for investment purposes, authorities said.
Ten million baht is worth nearly $280,000 (£215,000).
Confusion and mystery had earlier surrounded the discovery of the bodies, with local reports initially suggesting there had been a shooting.
Police later dismissed these reports.
Thailand’s Prime Minister Srettha Thavisin visited the hotel on Tuesday and ordered an urgent investigation into the case, stressing that it was a “private matter” unrelated to national security.
A clearer picture is emerging now of what might have happened.
In a press conference on Wednesday, Deputy Bangkok police chief Gen Noppassin Poonsawat said the group had checked into the hotel separately over the weekend and were assigned five rooms – four on the seventh floor, and one on the fifth.
They had been scheduled to check out on Monday but failed to do so.
Four of the victims are Vietnamese nationals Thi Nguyen Phuong, 46, her husband Hong Pham Thanh, 49, Thi Nguyen Phuong Lan, 47, and Dinh Tran Phu, 37.
The other two are American citizens Sherine Chong, 56, and Dang Hung Van, 55.
The US state department has offered its condolences and said it is “closely monitoring” the situation.
The US Federal Bureau of Investigation is assisting Thai authorities in the investigation, Mr Srettha said.
Police say on Monday afternoon all six victims had gathered in the room on the fifth floor.
The group ordered food and tea, which was delivered to the room around 14:00 local time (08:00 BST) and received by Ms Chong – who was the only person in the room at the time.
According to the deputy police chief, a waiter offered to make tea for the guests but Ms Chong refused this. The waiter recalled that she “spoke very little and was visibly under stress”, authorities said.
The waiter later left the room.
The rest of the group then began streaming into the room at various points, between 14:03 and 14:17.
No one else is believed to have entered the room apart from the six inside and police have said the door to the room was locked from within.
Police say there were no signs of a struggle, robbery or forced entry.
They later found traces of cyanide in all six tea cups.
Pictures released by the police show plates of untouched food left on a table in the room, some of them still covered in cling wrap.
There was a seventh name on the group’s hotel booking, whom police identified as the younger sister of one of the victims.
She had left Thailand last week for the Vietnamese coastal city of Da Nang and is not involved in the incident, police said.
Relatives interviewed by the police said Thi Nguyen Phuong and Hong Pham Thanh, a couple, owned a road construction business and had given money to Ms Chong to invest in a hospital building project in Japan.
Police suspect that Mr Tran, a make-up artist based in Da Nang, had also been “duped” into making an investment.
Mr Tran’s mother Tuý told BBC Vietnamese that he had travelled to Thailand on Friday and had called home on Sunday to say he had to extend his stay until Monday.
That was the last his family had heard from him.
She rang him again on Monday but he did not answer the call.
Ms Chong had hired Mr Tran as her personal make-up artist for the trip, one of his students told BBC Vietnamese.
Mr Tran’s father, Phu, told Vietnamese media that his son was hired last week by a Vietnamese woman to travel to Thailand.
The six bodies were discovered one day after Thailand expanded its visa-free entry scheme to travellers from 93 countries and territories to revitalise its tourism industry.
The Grand Hyatt Erawan is located in a district popular with tourists – however the area has also been the site of several high-profile crimes in recent years.
Last October, a 14-year-old boy shot and killed three people at the Siam Paragon mall just a few hundred metres down the road from the hotel.
The hotel sits opposite the Erawan Shrine, which was hit by a bomb blast in 2015 that killed 20 people.
The cyanide poisoning case prompted Prime Minister Srettha to reassure the public that Thailand has put in place security measures for tourists.
Tourism is a key pillar of the Thai economy, but it has not fully recovered from the coronavirus pandemic.
