Zhen Xiaojiang (second from right) during a previous court appearance. Zhen Xiaojiang (second from right) during a previous court appearance. (CNA photo)

TAIPEI (Taiwan News) - The retired Chinese military officer at the center of Taiwan’s biggest spy scandal was deported to China last Monday after serving out his prison term, the Apple Daily reported Wednesday.

Captain Zhen Xiaojiang (鎮小江) was found guilty in 2015 of recruiting active and retired Taiwanese military officers to collect confidential information on China’s behalf. He was sentenced to four years in prison and reportedly released on July 11.

After spending five nights at a special detention center for foreigners in Sanxia, New Taipei City, Zhen was put on a China Airlines flight to Hong Kong last Monday, July 16, because he has a Hong Kong passport, the Apple Daily reported.

Traveling on a tourist visa issued in the territory, Zhen started frequent travels to Taiwan as long as ten years ago, reports said. On those trips, he contacted officers from Taiwan’s military in order to spy for him. His top recruit was retired Army Major-General Hsu Nai-chuan (許乃權), who was later sentenced to two years and ten months in prison. He was the highest-ranking Taiwanese military officer ever to be prosecuted for violations of national security, the Central News Agency reported.

Four other retired officers were also sentenced during trials that were closed to the public due to the sensitive nature of the military information being discussed.

Zhen’s efforts reportedly succeeded in passing on information to China about Taiwan’s French-made Mirage 2000 jets and about advanced radar installations.