HANGZHOU, China - The key witness in the Sun Yang case has explained why he was absent from a public hearing, saying that he was willing to give testimony but nobody contacted him.

"I told them I would like to give my testimony through telephone or video conference as they suggested. I was ready; however, nobody had ever contacted me," said the witness on Wednesday who asked Xinhua not to be named.

"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.

The witness, one of the three doping control testers from the international testing company IDTM in Sun Yang case, said he had never been trained as a tester.

"I am a construction worker. My daily job is doing the construction work at construction sites. I am so busy that I don't have time to travel to Switzerland to attend the public hearing. No one had ever talked about doping control to me, not to mention such kind of training. It is unnecessary for me."

The witness said he had provided his statement in a written letter in Chinese during mid-October, introducing what he knew and experienced in that night.

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

Three-time Olympic champion Sun Yang declared his innocence at a Court of Arbitration for Sport (CAS) public hearing held in Montreux, Switzerland on November 15, after the World Anti-Doping Agency (WADA) appealed against him and swimming world governing body FINA over FINA's previous decision in favor of Sun on his alleged anti-doping rule violations.

In the interview with Xinhua, the witness said he had no idea what IDTM is, nor did he have any idea what he should do as a Doping Control Assistant (DCA).

"What is IDTM? What is DCA? What does it mean? I am not an assistant to any other company apart from my own construction job. How could I have relationship with them? Never!" he said.

"The only connection with them was on the night when my high school classmate gave me a phone call and asked me to pick up her at the railway station and drive her and another lady (the Blood Collection Assistant) to Sun's home. I was just off my work, so I drove them to Sun's home. She asked me to supervise Sun Yang's urination only when we stepped into the club house," he recalled.

"I was too excited to see Sun Yang. He was a super star in China and I took some photos of him. When he found out I was taking pictures of him, he asked me to delete the photos. I did so at Sun's request."

Sun later refused to complete the doping test conducted by IDTM testers on September 4, 2018 after discovering that the Doping Control Officer (DCO) and her assistants lacked sufficient authorization and credentials. The three testers signed an agreement with Sun on the early morning of September 5 stating that the test was "incomplete."

During the public hearing, it was said that the DCA had signed the Non-Disclosure Agreement (NDA) with IDTM company.

"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," said the witness in a surprise.

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

The witness said he wanted to make something clear: "I am an honest person. I am a construction worker, I have never related to doping control matters, no training, no DCA, no NDA, no IDTM," he declared.

CAS said on Tuesday that its verdict over the case brought by the WADA against Sun is not expected before mid-January 2020 due to poor translation of the testimony given by Sun and his witnesses. Lawyers of both parties had to constantly repeat their questions and even interrupt the witnesses' testimonies as a result of incomplete and inaccurate interpretation between Chinese and English.