Prosecutors have raided the home of former presidential secretary for civil affairs Woo Byung-woo... on suspicion of dereliction of duty.
They've also sought an arrest warrant for a music video director, who's believed to have helped Choi Soon-sil,... the woman at the heart of the abuse of power scandal.
Kim Jung-soo reports.
Seoul prosecutors on Thursday raided the home of former presidential senior secretary for civil affairs Woo Byung-woo on suspicion of dereliction of duty... for failing to prevent Choi Soon-sil from exerting influence over Cheong Wa Dae.

Woo had been summoned last Sunday for an intense 15-hour interrogation and was released early Monday, but that was for unrelated charges of embezzlement and abuse of authority.

Also on Thursday, prosecutors announced that they will seek an arrest warrant for advertisment and music video director Cha Eun-taek, who was summoned Wednesday for a second round of questioning.

Cha is believed to be a friend of Choi Soon-sil, and is also suspected of having played an important role in the establishment and management of the Mir Foundation, to which Choi allegedly forced some of Korea's leading conglomerates to donate.

Meanwhile, it appears prosecutors have found even more links between Choi and President Park.

The head of the Seoul Central District Prosecutors' Office's found evidence on Thursday that former secretary for public relations planning Ahn Bong-geun, and former secretary for adminstrative affairs Lee Jae-man, had helped Choi Soon-sil -- a private citizen with no security clearance -- access presidential office documents.

The news comes just a day after prosecutors raided the homes of the two aides, who had resigned from their positions at the end of last month.

Together with President Park's personal secretary Jeong Ho-sung, the three former aides had served Park for more than two decades, and were called by Cheong Wa Dae insiders "the three doorknobs."

According to the Prosecutor's Office, Lee