A senior police constable in Hong Kong had an intimate relationship with a detained woman he visited using the forged signature of his supervisor, a court was told on Tuesday.

Prosecutor Fanny Wong Kam-hing told Eastern Court that detective constable Cheung Ka-lok, 43, wrote at least two greeting cards to the woman, who in return sent him 45 letters and handed him her diary.

The court heard that one of the cards had the Chinese character for “luck” on its cover, while the other card had the English word “wife” printed on its cover and “love” on the inside.

Defence lawyer Chan Pak-kong said his client did not dispute the prosecution’s case that he had an “intimate relationship” with the woman before he allegedly forged the first memo of request on January 11, 2017, which allowed him to visit her in barrier-free, one-on-one sessions with no time limits.

Deputy magistrate Vivian Wong Wing-man ruled on Tuesday that the prosecution had established sufficient evidence for the trial to continue.

“The defendant has a case to answer,” she said.

Cheung, who has pleaded not guilty to two counts each of possessing and using a false instrument, will give evidence in court on November 28.

On Monday, the court heard that Cheung, a senior detective at the Organised Crime and Triad Bureau before arrest, had twice visited the woman in Tai Lam Centre for Women on January 11 and 25, 2017, when he was serving in Wan Chai’s Regional Anti-Triad Unit.

He allegedly used two false memos of request purportedly signed by his supervisor, senior inspector Ho Wai-man. Ho denied authorising Cheung to make the visits.

The magistrate granted a gagging order on Tuesday to protect the identity of the woman, after the defence asserted she was an unregistered informant who had offered leads to assist Cheung’s drug trade investigations.

Station sergeant Lee Chi-lai, who initially planned to meet the woman alongside Cheung in Tai Lam Centre on January 10, 2017, said he and Cheung came to know the woman in around September or October 2016, when they were probing drug trafficking in Tsim Sha Tsui and Wan Chai.

“I don’t know [the woman] personally, but I do have knowledge of her as she had connections with people selling drugs,” Lee said, adding he did not notice any unusual conversations or body contact between Cheung and the woman when the three of them first met.

The proposed meeting on January 10 was unsuccessful, he said, after they had mistaken the woman’s prisoner number. He said he did not make it to the meeting the following day as he was occupied by other matters.

Sergeant Lai Ka-kin, another supervisor of Cheung, said detectives were required to report to their superior when they visited a prison, but he had “no impression” that Cheung informed him about making visits in January 2017.

Prosecutor Wong said that after Cheung’s arrest on February 5 last year, police had seized several documents, a computer hard disc and a mobile phone from Cheung’s office.

Wong said police had discovered, alongside greeting cards, letters and diary, a photo album containing 23 pictures, some of which were portraits of the defendant and the detained woman.

Police also found in the hard disc the electronic version of a memo of request dated January 10, which asked for permission from the Commissioner of Correctional Services to allow Cheung and Lee to meet the woman. Chan confirmed the memo was indeed prepared by his client.