The Seoul Central District Prosecutor's Office said Wednesday that an investigative team had searched the home of former National Intelligence Service(NIS) official Lee Heon-su and the office of an organization composed of ex-police officers.

Prosecutors confiscated mobile phones, data from hard drives and personal documents to secure evidence regarding accusations that the NIS was involved in the Park Geun-hye administration's demand to corporations to pay conservative groups to hold rallies supporting the government.

The prosecution is expected to delve into whether the NIS had been involved in the leaking of phone transcripts between Seoul and Pyongyang during the 2012 presidential elections in the South.

An investigation by the NIS's own reform committee recently found that the agency had been involved in a series of political maneuvering and plans to request the prosecution for a probe. Former NIS Director Nam Jae-joon and conservative politician Kim Moo-sung will likely be questioned, as well as then-members of the Saenuri Party's electoral committee.

The NIS reform committee is also expected to ask for an investigation into the agency's role in drawing up a blacklist of cultural figures critical of the government.