About the same time, another group of prosecutors searched Lee's office in Suwon in the presence of the governor and his lawyer.

The raid was apparently intended to retrieve an iPhone used by Lee's wife, Kim Hye-kyung, from July 2016 until April this year, when allegations of her involvement in online slandering of Lee's election rivals surfaced.

Kim, who is suspected of posting slanderous messages on social media sites via her mobile phone, changed her iPhone and phone number in April and told police investigators later that she was not aware of its whereabouts.

Police recently identified the owner of the Twitter ID "Hyekyunggung Ms. Kim," who left numerous defamatory comments before and during elections in recent years, as Kim.

Police suspect she wrote comments in December 2016 against President Moon Jae-in, then Lee's potential rival in the Democratic Party's primary for the 2017 presidential election. She accused Moon of using his influence to help his son land a job at a public institution years ago.

Police also claimed she wrote in April this year that one of Lee's rivals in the DP primary for the Gyeonggi Province gubernatorial election collaborated with the conservative opposition Liberty Korea Party.

She faces charges of defamation and spreading of false information.

Prosecutors believe Kim used the missing iPhone to write the two controversial posts.

Tuesday's raids came eight days after police referred the case to the prosecution with an opinion of indictment.

Kim was previously questioned by police but strongly denied any wrongdoing. Lee, former Seongnam mayor, has denounced the police for making politically motivated, baseless accusations while disregarding any evidence in Kim's favor. (Yonhap)