Netiporn "Bung" Sanesangkhom, 28, passed away after her heart "stopped suddenly" in the early hours of May 14, officials confirmed.
Netiporn, a prominent member of a youth movement advocating for royal reforms, had been detained since January 26, facing seven separate charges, including two of insulting the monarchy, according to the BBC. She began her hunger strike the day after her detention, accepting only water until late February and resuming food intake in April.
The activist, who was the daughter of a judge, drew significant attention to the stringent enforcement of Thailand’s controversial lese majeste law, which imposes penalties of up to 15 years in prison for critics of the monarchy.
Initially held on a contempt of court charge, her detention was extended after bail in a separate lese-majeste case was revoked.
Earlier this year, a 30-year-old Thai man was sentenced to a record 50 years in prison for insulting the royal family through numerous social media posts perceived as critical of the monarchy.
The lese majeste law has been part of Thailand's legal system since the first criminal code was established in 1908. However, prosecutions under this law had been paused for nearly three years until November 2020, when then-Prime Minister Gen. Prayut Chan-ocha ordered their resumption amid growing criticism of the monarchy, according to Human Rights Watch.
Thailand’s revered King Bhumibol Adulyadej, who died in October 2016 served as the monarch for seven decades. His son, Maha Vajiralongkorn has since succeeded him on the throne.