One of the activists demanding an investigation into Rajabhakti Park has reportedly been taken and held incommunicado by the Thai authorities.

Chatmongkon Wanli, a 21-year-old activist, who was earlier forced to sign a memorandum of understanding (MoU) promising not take part in any political activity, posted a message on his Facebook page on Sunday, 21 December 2015, that his fellow activist has been missing for three days.

“My friend has gone missing for three days. [His name is] Nueng Katesakun, 28, from Bang Bua District, Bang Kaen Sub-district, Bangkok. Please contact me if [you] see him,” reads Chatmongkon’s message.

Panita Chanwankanong, 52, the mother of the missing activist, confirmed to Prachatai that Nueng, a 29-year-old activist who was one of the 36 activists detained en route to Rajabhakti Park earlier this month, has gone missing from his house for at least two days.

His sister who lives in the same house as Nueng told Prachatai that her brother has been missing since the late afternoon of Saturday, 19 December 2015, and that there was no sign that he planned to stay elsewhere because he did not take any extra clothes with him.

On 19 October 2014, Nueng was arrested by four plainclothes military officers on his way home from the funeral of Apiwan Wiriyachai, the late red-shirt leader and ex-Pheu Thai Member of Parliament.

The military claimed that Nueng attempted to destroy a military vehicle during an anti-junta protest at Victory Monument in Bangkok on 28 June 2014.

Songtham Kaewpanpruek, another pro-democracy activist, reported that six plainclothes officers arrested Nueng on 17 December and took him to Phahonyothin Police Station.

He was last seen at the military court last week when he came to support Thanet Anantawong, a 25-year-old activist facing sedition charges recently bailed by the military court.