The doctor involved in the HIV registry data leak told a court yesterday that he was "afraid of being penalised" under Section 377A of the Penal Code for providing prostatic massages, and decided against telling narcotics officers about it.

The law criminalises sex between consenting male adults.

Ler Teck Siang, 38, is accused of injecting narcotics into abusers for a fee in a practice that is known as "slamming".

He had denied providing the drug injections earlier in the trial, claiming he had instead given sports and prostatic massages to drug abuser Sim Eng Chee.

Sim, who is serving a sentence for drug consumption and possession, had testified that he hired Ler for "slamming" services before sex parties with other men.

On the sixth day of Ler's trial, the medical doctor told a district court that he did not mention this prostatic massage services to Central Narcotics Bureau (CNB) officers as he was "not certain if it would constitute" an offence under Section 377A in the Penal Code.

He said he did not provide such services in the "capacity of a medical professional", adding that he was embarrassed that he did offer prostatic massages.

"It's a private and personal kind of service I was providing...not something I'd want to share with a narcotics officer," said Ler.

He is contesting one charge of injecting methamphetamine, also known as Ice, into Sim on Feb 26 last year, and another charge of possessing drug-related utensils a few days later on March 2.

Narcotics officers had reportedly found a methamphetamine-stained syringe and straws on Ler when they arrested him and Sim at Conrad Centennial Singapore.

Yesterday, Ler's former business partner - Dr Ng Tsorng Chinn, the director of Faith Medical Group - took the stand to testify that Ler was a "good man".

Ler, who is representing himself, asked Dr Ng to explain what the syringe that CNB officers found on him is typically used for.

Dr Ng said it is meant for subcutaneous injections like when injecting insulin, adding that it is "too soft, too small, too short" to be used for intravenous injections. "Slamming" involves intravenous injections.

Ler's friend, Mr Lefebvre Chris Bryan, also took the stand to testify that he was present on the two occasions when "slamming" sessions allegedly took place involving Sim.

He said he saw Ler only dressing Sim's wound and did not witness Ler administering drugs into Sim.

However, during cross examination, Deputy Public Prosecutor Nicholas Wuan charged that Mr Lefebvre was lying to protect Ler, noting that he was in court because of his close relationship with Ler. Mr Lefebvre denied this.

The trial will resume next month.

Both Ler and his former American partner, Mikhy Farrera-Brochez, are at the heart of the HIV registry data leak where details of 14,200 HIV-positive patients here were leaked online.

Farrera-Brochez was found guilty of three charges against him, relating to stolen identification documents from Singapore, by a United States court on June 4 and will be sentenced on Sept 27.

The Ministry of Health also has a civil suit ongoing in Kentucky to compel him to delete and return the stolen HIV registry data.