The footage of the party was never publicly discussed in Thailand’s news media.
The crown prince’s marriage to Ms. Srirasmi blew up spectacularly in 2014, when members of her family were suddenly swept up by the police, charged and brought to trial.
At least three of Ms. Srirasmi’s siblings were sent to prison for crimes including illegal possession of firearms and insulting the monarchy, according to police statements. Her mother and father were sentenced to prison for insulting the monarchy.
Her uncle Pongpat Chayapan, a high-ranking police officer, was convicted of running illegal casinos, oil smuggling, money laundering and other crimes.
Ms. Srirasmi gave up her royally bestowed name, according to an entry in The Royal Gazette, but she was given a stipend of more than $5 million of government funds from the Crown Property Bureau, a payment made public in a letter signed by the junta chief.
The purge reinforced fears of an ominous, violent side in the prince’s entourage.
One of a handful of police officers purged in the 2014 separation, Akkharawit Limrat, died under mysterious circumstances, his body hastily cremated, according to a funeral certificate published in the Thai news media.
The police, calling the matter “sensitive,” gave only scant details.
Lt. Gen. Prawut Thavornsiri, then the police spokesman, described the death this way: “He got stressed out. So he jumped out of the building and died.”
A separate purge last year of aides to the crown prince had a similar outcome. Two of the three men arrested died in custody in military barracks.