Panthongtae Shinawatra has complained about the public release of security footage of him visiting the Department of Special Investigation (DSI) to answer money laundering charges last Tuesday.
The release of the pictures to the media represented a violation of his rights, the son of former prime minister Thaksin Shinawatra wrote on his Facebook page on Friday evening.
Mr Panthongtae said that when he arrived at the DSI, its staff told him they had to proceed carefully because former prime minister Abhisit Vejjajiva had complained earlier after images of him visiting the DSI to answer a charge were released.
Mr Panthongtae said he told the staff that such images could come only from the DSI's overhead surveillance cameras because no one else would be able to enter the office and take photographs.
DSI staff then assured him that such cameras were used only for security purposes and not for any release to media, he said.
But his photo ended up being released to the media anyway, and Mr Panthongtae said a DSI spokesman admitted to sending it to prove that he had gone to the agency to acknowledge the charges against him.
"If an upstream justice organisation offers justice with the violation of other people's rights, how can people expect justice from it?" Mr Panthongtae wrote.
Mr Panthongtae and three others are accused of laundering some of the money lent to subsidiaries of the property developer Krisdamahanakorn by state-owned Krungthai Bank (KTB) in 2003 and 2004, when his father was prime minister, even though the company was a non-performing debtor.
Prime Minister Prayut Chan-o-cha earlier this year ordered the Royal Thai Police to stop parading criminal suspects before the cameras in staged photo opportunities, saying such actions violated people's rights. However, the police continue to routinely ignore the order.