Thailand's Princess Bajrakitiyabha, who has been in a coma for more than three years, has died, the royal household has announced. She was 47.
In December 2022 the Princess had been hospitalised following a collapse while out walking her dogs on December 14.
Her doctors attributed it to a severely irregular heartbeat, caused by a mycoplasma infection in her heart. She was the eldest of King Vajiralongkorn's seven children, born on 7 December 1978 to his first wife and cousin, Princess Soamsawali.
According to BBC "The medical team provided the closest and most intensive care possible, but her condition continued to decline progressively," the palace said in a statement on Friday morning, adding that she passed away at 19:48 local time (12:48 GMT) the previous day in Chulalongkorn Hospital.
She trained as a lawyer, getting two post-graduate degrees from Cornell University in the US. She worked briefly at the Thai mission to the United Nations in New York, before returning to Thailand to work in the Attorney-General's offices in Bangkok and elsewhere in the country.
According to BBC King Vajiralongkorn, who is 73 years old, has not yet named an heir.
Thai custom dictates that the heir should be a male, but a 1974 amendment to the constitution does allow a female to take the throne.
The king has five sons, but four by his second marriage were disowned in 1996 and have lived since then with their mother in the US.
His fifth son, Dipangkorn, by his third wife, is the presumed heir, although questions have been raised about his ability to perform the role of monarch, in a country where the royal institution carries so much influence.
According to BBC Thai royalists, Princess Bajrakitiyabha seemed the most promising figure to succeed her father, either as queen or as a regent to help Prince Dipangkorn.
Her death leaves the question of the succession in Thailand unanswered, and the severity of the country's lese majeste law rules out any public discussion of it.