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 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 grim discovery of the bodies, with local reports initially suggesting there had been a shooting. Police later dismissed these reports.
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.
On Monday afternoon, all six of them 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.
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 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 US Federal Bureau of Investigation is assisting Thai authorities in the investigation, Thailand’s Prime Minister Srettha Thavisin has said.
Additional reporting by BBC Thai and BBC Vietnamese’s Thuong Le
