On the fifth day of his trial on espionage charges on Monday, Australian filmmaker James Ricketson told the Phnom Penh Municipal Court how his “illegal” arrest was carried out without a warrant and may have resulted from a case of mistaken identity.

“I believe the accusation that I’m an American spy is a mistake,” he said Ricketson said he had never had any links to any government or military.

“During my detention, I heard that there was a man named James – like me – who [was friends] with [former Cambodia National Rescue Party (CNRP) leader] Kem Sokha’s daughter Mona,” the 69-year-old said.

“[The police] could have [mistakenly] believed that I was an American spy and that’s why they arrested me. It was a mistake and I thought that the mistake would be corrected in a few weeks, but it still hasn’t been,” he said, in response to a question from his defence lawyer, Kong Sam Onn.

Ricketson detailed being taken into custody on June 3, 2017, which he said was carried out “without an arrest warrant”.

The previous day, he said, he had flown a drone over an opposition CNRP rally near the capital’s Japanese Bridge during campaigning for that year’s commune elections.

“I thought the police might have thought I took pictures of somewhere I wasn’t allowed to,” he said, referring to flying his drone over the rally.

“No one told me to capture the video footage, and I sent the video to the CNRP,” he added.

Ricketson said he wasn’t arrested while flying his drone over the rally, but rather the next day while sitting with his goddaughter and another woman on Riverside around 500 metres north of the Royal Palace Garden at 5pm.

“A man in plain clothes came to talk to me,” Ricketson said. “He said he was from the immigration department. Then 12 uniformed policemen arrived and asked for my passport.

“I said I kept it at my guesthouse. They said, as a foreigner, I had to keep my passport with me all the times.”

Ricketson said the police asked him to go with them to the station for questioning without showing an arrest warrant. Three police officers put him into the back seat of a car.

He said he refused to answer questions without the presence of a lawyer.

On the morning of June 4, he said, police brought all his belongings from his guesthouse and put them in front of him, including two mobile phones, three cameras, and a laptop.

Ricketson said he agreed to let police check his phones but not the laptop. However, he said, 11 months later, the court had shown him 1,600 pages of documents taken from his computer.

During his pre-trial detention, he said he had asked to know who had filed the complaint against him. He also requested the opportunity to challenge the police and prosecutor Sieng Sok.

“I wanted to know what my crime was, who was the victim, who filed the complaint and who were the witnesses? But the investigative judge didn’t respond to my requests.

“Even now I don’t know who filed the complaint, who was the victim and who the witnesses were,” he said.

The court was adjourned until Tuesday, which Presiding Judge Seng Leang said would be the final day of the trial.