Chen's office issued a statement that accused SIP prosecutors Chu Chao-liang, Wu Wen-chung, Lee Hai-lung and Yueh Fang-ju of violating judicial procedures while they were investigating the former president, the Taipei Times said Friday.
"The SIP prosecutors abused their right to arrest Chen despite his innocence and to negotiate with Jeffrey Koo Jr. in Japan although he is guilty," Chen's office alleged, referring to the former Chinatrust Financial Holding Co. vice chairman.
Chen's lawsuit, filed Thursday, alleges the prosecutors committed extortion, solicitation and forgery during their investigation, along with violating judicial neutrality in their handling of witnesses.
Chen has been indicted on corruption charges and is seeking to determine if the prosecutors got Koo to testify against him by reaching a deal with the Chinatrust official, the Times said.
A SIP spokesman had no comment on Chen's lawsuit, whose specific details weren't reported, the Times said.