Fifteen months on, Sun Yang still struggles to process the events of the night that has become a legal nightmare for China's Olympic champion.

"Everything that happened on the night of September 4, 2018 looked bizarre," recalled Sun after his morning training session in Beijing on Wednesday.

"The doping officials didn't have sufficient credentials, one official had never received any training in doping control, and they agreed not to take away my samples because they lacked the proper credentials.

"The funny thing is that they brought with them a foam box like one for storing seafood, instead of a standard collection box," added the three-time Olympic and 11-time world champion.

Sun was tested by Chinese anti-doping officials on Tuesday night, his 25th check of the year. He said the Chinese officials "performed their duty exactly as required by the WADA (World Anti-Doping Agency) code and used standard testing equipment".

The 28-year-old has been tested nearly 200 times since 2012, including 28 tests in 2017 and 31 in 2018.

The Court of Arbitration for Sport (CAS) said on Tuesday that its verdict in the WADA case against Sun is not expected until mid-January, partly because it is taking so long to prepare a written transcript of the Nov 15 hearing, which was marred by poor translation.

Sun refused to complete a doping test conducted by international testing company IDTM at his home on Sept 4, 2018 after discovering that the doping-control officer (DCO) and her assistants lacked sufficient authorization and credentials.

The three testers signed a statement with Sun on the morning of Sept 5, which specified that the test was "incomplete" and that they would not take away the swimmer's samples.

Sun's case was later heard by swimming's world governing body FINA, which in January 2019 decided that the swimmer was not guilty of anti-doping rule violations. WADA disagreed, appealed the decision and asked the court to ban Sun for between two and eight years.

At Sun's request, last month's hearing in Montreux, Switzerland, was only the second public proceeding in the history of CAS.

Sun said that he wanted the hearing to be made public to let the world know what happened and to prove his innocence.

In an earlier interview with Xinhua, Sun said he couldn't trust testers that did not have sufficient documentation to prove who they were.

"I refused to take a urine test in front of a man who wasn't a real tester," Sun said.

"When I take a urine test, I have to roll up my sleeves up to elbows and have my pants down to my knees. I can show my body to doctors or official testers. How can I urinate in front of a total stranger who isn't a tester or doctor?"

Missing testimony

One of the doping-control assistants (DCA) on the night, who asked not to be named, told Xinhua that he was a construction worker by profession, had never been trained in doping control, and was only at Sun's home on the night in question at the request of the DCO, who was a former high school classmate of his.

On Wednesday, the same person, who again spoke on condition of anonymity, told Xinhua that he had been willing to testify at the Nov 15 CAS hearing but nobody contacted him.

"I told them I would like to give my testimony via telephone or video conference as they suggested. I was ready, however nobody ever contacted me," he said.

"I felt like they did not seriously expect me to show up and give my words in the court. Maybe they just asked me in a casual way."

He added: "My daily job is doing construction work at construction sites. I am so busy that I don't have time to travel to Switzerland for public hearings. No one had ever spoken to me about doping control, not to mention any such kind of training. It is unnecessary for me."

The stand-in DCA said he had provided a written statement in mid-October, outlining what he knew and experienced on the night of the test.

"It was the first time someone from the international organization asked me about this matter in a year. I just got to know this case was upgraded to an international appeal," he said.

During the CAS hearing, it was alleged that a DCA had signed a non-disclosure agreement (NDA) with IDTM.

However, the temporary DCA said: "Did someone say that? I was totally unclear about it. What does NDA mean and what is in it? I have no idea and no one had talked about it with me.

"My classmate came to me a couple of times in the early morning on September 5, 2018, and showed me something on the iPad. It was all in English! I could not understand it at all, so I returned it to her. I did not sign my signature on it. Is that what you call an NDA?

"I am an honest person. I am a construction worker, I have never previously been associated with doping-control matters－no training, no DCA, no NDA, no IDTM."