Monta "Ying Kai" Yokrattanakan, accused by former employees of lodging false theft complaints against them, was found to have requested a psychiatric patient card from a hospital in Nonthaburi.
This was revealed by lawyer Songkan Atchariyasap, chairman of the Network Against Acts that Destroy the Kingdom, Religion and Monarchy, citing a police investigation.
Mr Songkan said the probe, ordered by Central Investigation Bureau commissioner Thitirat Nongharnphithak, discovered Ms Monta had submitted the request for the document at a private hospital in the Khae Rai area.
Pol Lt Gen Thitirat said earlier Ms Monta may have a mental illness because she cannot control her behaviour at times and advised she seek treatment.
Mr Songkan said although Ms Monta has obtained the document, the law clearly stipulates people cannot cite their illness to bolster their defence if they plan and commit wrongdoing with the understanding of the consequences.
The lawyer on Sunday took Ms Monta's former employees -- Praphawan Jaikla, her parents Chukiat Jaikla and Prapaporn Thongfuang, and Sukanya Sirimuang -- to petition the Crime Suppression Division (CSD), asking them to investigate officials, including the police, who may have colluded with Ms Monta to commit crimes. Ms Monta is in jail awaiting the results of various probes.
Mr Songkan said some high-ranking officers, including the police and military, may have been aware of Ms Monta's wrongdoing or assisted her in the offences.
The CSD has been asked to investigate the matter before forwarding its report to the Public Sector Anti-Corruption Commission (PACC) and the National Anti Corruption Commission (NACC), he said.
Ms Monta is facing charges of making false complaints to police, attempted human trafficking and insulting the royal institution.
Ms Monta came under new scrutiny after Mr Songkan said on Friday her trusted driver mysteriously disappeared four years ago, as did a millionaire from whom she asked to buy an eight-rai land plot in Udon Thani in 2003.
Based on the millionaire's case, Mr Songkan said Ms Monta, escorted by tourist police cars, picked up the wealthy woman at her house in Udon Thani's Muang district in December, 2003, citing claims by her relatives and nearby villagers. The millionaire went missing afterwards. The land ownership was later transferred to Ms Monta and it was resold a month later.
When Ms Monta applied for passports and travelled to Mae Hong Son, where she crossed into Myanmar, witnesses confirmed there were state officials in uniform assisting her, Mr Songkan added.
Referring to the probe into Ms Monta's assets, CSD deputy chief Chakrit Sawasdee said Sunday the woman's income only comes from her car wash service and she is not as rich as she claimed.
More than 10 million baht worth of valuables, which Ms Monta claimed were stolen by her employee, were unlikely to exist. Pol Lt Gen Sanit Mahathavorn, acting chief of the Metropolitan Police Bureau (MPB), said a panel had been formed to probe five Pracha Chuen police, who took up Ms Monta's nine complaints against her employees on theft charges.