About 30 white masks of the anti-government V For Thailand movement rallied in front of the office of the Department of Special Investigation (DSI) on Thursday in protest against Tarit Pengdith and threatened to seek legal and disciplinary action against him for alleged violation of Section 112 of the Criminal Code, the lese majeste law.
The white masks, led by Bovorn Yasinthorn, were dissatisfied that Mr Tarit, the DSI chief, has accepted for investigation as a special case a complaint against Mallika Boonmeetrakul, the deputy spokeswoman of the Democrat Party.
The complaint was filed by Winyat Chartmontree, a lawyer for the red-shirt United Front for Democracy against Dictatorship (UDD).
In the complaint, Ms Mallika is accused of posting on her Facebook and Twitter pages a doctored picture of Prime Minister Yingluck Shinawatra on a signboard in a way that could be taken as insulting.
Ms Mallika is accused of violating the Computer Crimes Act.
Mr Tarit said the DSI took up the case because it concerns an alleged offence under the cyber crime law and also the prime minister, who he said was "the head of state".
His Majesty the King is the constitutional head of state.
Mr Bovorn said it was inappropriate that Mr Tarit had referred to the prime minister as "the head of state", and this could be a violation of Section 112 of the Criminal Code, the lese majeste law.
He said the white masks would also submit a letter to Justice Minister Chaikasem Nitisiri, asking him to suspend Mr Tarit from duty and set up a committee to urgently conduct a serious disciplinary investigation against the DSI chief.
They would also file a complaint with Pol Gen Adul Saengsingkaew, the police chief, accusing Mr Tarit of lese majeste.
A similar complaint would also be submitted to Ms Yingluck, Mr Bovorn said.
Mr Tarit explained that he acturally meant to refer to the prime minister as head of the administrative branch, one of the three sovereign powers of the country. The other two are the judicial and legislative branches.
Mr Tarit said he is loyal to the monarchy and has never thought of doing anything which may be construed as offending the high institution.
He claimed that those who accused him in public could themselves also be seen as committing lese majeste.