The prosecution withdrew the allegedly forged evidence against former Seoul City official Yoo Woo-seong on Thursday, effectively admitting that the documents were fabricated.

Yoo, a North Korean-Chinese who came to the South in 2004, is accused of spying for Pyongyang. Although the case was initially thrown out for lack of evidence, the prosecution appealed using Chinese government documents secured by the National Intelligence Service.

However, allegations surfaced that the documents, including immigration records supposedly proving that Yoo entered North Korea as late as 2006, were forgeries, undermining the prosecution’s case and implicating the NIS in an unprecedented scandal.

“Various circumstances that raise questions about their authenticity have arisen, but it will be difficult to obtain materials to prove that they are real,” the Seoul Central District Prosecutors’ Office said.

The prosecution will not, however, drop the case against Yoo.

“After reviewing relevant records, the prosecution decided that Yoo’s spy charges would be acknowledged by the court without the documents,” said Yoon Woong-keol, senior prosecutor at the Seoul Central District Prosecutors’ Office, was quoted as saying by a local news agency. Yoon also said that the authorities will continue to try to prove Yoo’s espionage charges and that new evidence will be submitted to the Seoul High Court.

In addition to the documents, the prosecution removed a former Chinese government official from its list of witnesses, backing down entirely from the controversy. The former Chinese official, identified by the surname Lim, was to testify that the irregularities in the prosecution’s evidence may have been due to errors in the Chinese authorities’ database.

Although the prosecution appeared sure of the authenticity of the documents as recently as March 11, the developments in the probe into the NIS seem to have influenced Thursday’s decision.

Since the probe was launched to determine the NIS’ role in obtaining the documents in question, a midlevel NIS agent and a Korean-Chinese collaborator have been arrested in connection to the case.

The NIS collaborator, identified as Kim, told the investigators that the arrested agent ordered him to obtain forged documents and that the spy agency was fully aware of the situation.

Although all NIS officials questioned in the probe so far have denied the allegations, the probe has been creeping up the NIS chain of command. However, the investigation was brought to an unexpected halt following the suicide attempt of another key suspect.

In his suicide note, Kwon claimed that the prosecution was attempting to frame the NIS in order to protect itself despite being aware that Yoo Woo-seong was guilty.

By Choi He-suk (cheesuk@heraldcorp.com)