The Central Academy of Drama on Friday stripped singer and actor Tong Zhuo of his graduation certificate after investigations by local authorities found that he had changed his identity during the national college entrance exam, or gaokao.

Three people were put under police investigation and another 12 people have been punished for aiding Tong in fabricating his identity, according to a notice by Shanxi's Linfen Commission for Discipline Inspection of the Communist Party of China and the Linfen Supervisory Commission on Friday.

The scandal broke when the singer was chatting with fans on a livestreaming platform late last month. "We used a lot of so-called guanxi (connections) and then I became a fresh high school graduate," said Tong, 26, laughing with one hand covering his mouth.

His cheating in gaokao soon stirred outcry from netizens, who demanded an investigation, despite his apology.

According to the Shanxi provincial education department, the singer changed his personal information to show that he was a fresh high school graduate before he took the gaokao in 2013 for the second time, so that he could be eligible to apply for a top art school that only accepted fresh high school graduates.

A separate investigation by Linfen's disciplinary watchdogs found that he had the identity changed with help from his stepfather, Tong Tianfeng, deputy secretary-general of the Linfen People's Congress.

Tong Zhuo first took the gaokao in Beijing under the name Li Zhenhua in June 2012 and was not admitted to his dream school, the School of Military Culture, National Defence University of the People's Liberation Army. He wanted to apply to the school again the next year. However, only fresh high school graduates are eligible to apply for the school.

So, Tong Tianfeng consulted Peng Bo, an education official in Linfen, about how to change Tong's personal information.

With help from Peng and a few others in the local education system, Tong Zhuo's identity was changed, and he took part in interview tests as a fresh high school graduate.

He was later admitted into the Central Academy of Drama.

Linfen's discipline watchdog said on Friday that Tong Tianfeng has been removed from office, and three education officials were put under police custody for allegedly forging documents.

According to the academy, Tong was admitted to the academy in 2013 and did not get a diploma from the university when he graduated in 2018 as he did not meet the requirements.

Tong said in his apology that he felt guilty.

"Public criticism has made me realize my mistake," he said in a written apology. "Gaokao is a very serious exam and no one should speak or act unlawfully to jeopardize its fairness and justice."