Chonthicha Jaengrew, a member of New Democracy Movement, posted on Facebook on Tuesday that she had been contacted by a person claiming to be a police officer who told her to stop investigating or taking any other action regarding the missing plaque. She could be prosecuted on national security charges, including lese majeste, she was warned.

Prior to Chonthicha’s case, two other pro-democracy activists who have protested the disappearance of the plaque, Sirawith Serithiwat and Piyarat Chongthep, posted similar message on Facebook about being called by police and warned against activities concerning the plaque.

The plaque was reported missing two weeks, when a replacement know as the so-called “Na Sai”, or “happy face people” plaque, was discovered.

Government officials have made vague statements and avoided taking any action on the matter.