(CNN)Australian filmmaker James Ricketson is set to be released from prison in Cambodia Friday after receiving a royal pardon, his attorney has told CNN.
The 69-year-old was arrested in Cambodia in June 2017 after flying a drone over a rally organized by the Cambodia National Rescue Party, an opposition group that was later dissolved by the government.
Ricketson was found guilty of espionage on August 31, 2018 and sentenced to six years in prison.
On Friday, Sam Onn Kong, Ricketson's attorney, told CNN that his client "never had any malicious intent toward Cambodia."
The attorney previously told CNN that during Ricketson's trial the prosecution was unable to provide any concrete evidence against him -- or even name the country that Ricketson was accused of spying for.
A statement released by Ricketson's family expressed relief, adding health concerns meant they were unsure "how long he could have continued to endure the conditions of the notorious Prey Sar prison."
Speaking to CNN Friday, Ricketson's son, Jesse, said the news had yet to sink in.
"We are just so relieved and excited about this news," he said. "It still hasn't really sunk in. It has been a really tough 16 months and I'm just kind of in shock right now.
"We would like to offer our hugest gratitude to king Norodom Sihamoni for showing us compassion and bringing this nightmare to an end. We are eternally grateful."
Ricketson has traveled back and forth between Cambodia and Australia for more than 20 years, filming documentaries about life in the Southeast Asian country.
In August, Jesse Ricketson told CNN that his father's first trip to Cambodia was to film "Sleeping with Cambodia," a 55-minute documentary described by Screen Australia as an "exploration of pedophilia and children at risk."
Since then he has set up charitable ventures in the country, including fostering a Cambodian girl, and her mother.