Jonathan Head, a British journalist with the BBC, appeared in a Phuket court Thursday after a lawyer brought a criminal defamation case against him over an investigation into fraud on the popular tourist island.
The prosecution was sparked by a September 2015 report by Head, the BBC's Southeast Asia correspondent, looking at how two foreign retirees were scammed out of their properties in Phuket.
Head appeared in court alongside one of the retirees, British national Ian Rance who is a joint defendant, to enter their pleas.
Both pleaded not guilty.
Witness hearings have been scheduled for three days in August, according to a source who asked not to be named.
The man bringing the prosecution is Pratuan Thanarak, a Phuket lawyer who featured in the BBC report looking at how Mr Rance lost lucrative properties.
Mr Rance retired to Phuket in 2001, married a local woman with whom he had three children and bought what he said were some US$1.2 million (41.9 million baht) worth of properties.
Under Thai law foreigners cannot own land. But many get around that provision by placing properties in the name of a company they own or with locals they trust.
In 2010, Mr Rance discovered his wife had forged his signature to remove him as director and sell the properties with the help of a network of money lenders and property agents on the island.
She was jailed for four years over the scam.
The BBC's Head reported Mr Pratuan, the lawyer, admitted to notarising Mr Rance's signature without him being present.
Mr Pratuan filed a defamation case saying the reports caused him to be "defamed, insulted or hated", according to a copy of the complaint seen by AFP.
Mr Rance and Head face one charge of criminal defamation, which carries up to two years in jail.
Head faces an additional charge under the Computer Crimes Act, which has a five-year maximum jail penalty. Head has had to surrender his passport to the court leaving him unable to work across Asia as he fights what is likely to be a two-year court battle.
The BBC said it "stands by its journalism" and it intends to clear Head's name.