Police raided the headquarters of Daewoo Engineering & Construction Co. on Friday as part of their probe into allegations that the country\'s third-largest builder received bribes from a local contractor who is currently embroiled in a highly publicized sex-for-favors scandal. The National Police Agency (NPA) has been looking into suspicions that the 52-year-old construction contractor, surnamed Yoon, provided various kickbacks to the construction firm through a broker in exchange for winning a contract to build a golf course in Chuncheon, Gangwon Province. Yoon is the builder who has been at the center of a snowballing scandal in which he allegedly hired women to provide sexual favors to a number of high-profile figures in return for business benefits. \"(The Friday\'s raid) was to secure relevant documents as there is circumstantial evidence of an alleged bribery exchange between Yoon and Daewoo Construction,\" a NPA officer close to the investigation said. The officer, however, said the raid has nothing to do with the sex bribery allegations. Yoon is suspected of offering lavish sexual entertainment between 2009 and 2011 to influential figures from all walks of life -- including former and incumbent ranking law enforcement officials and the head of a hospital -- at his vacation home in Wonju, Gangwon Province. In return, he allegedly gained business benefits, including winning construction contracts, or favorable treatment in several lawsuits against him. Yoon is also under suspicion that he sexually assaulted some of the women he hired for sex services after drugging them. The sources said police confirmed part of the drug-use charges after investigating those involved. Police are also expected to summon former Vice Justice Minister Kim Hak-ui, one of the people who allegedly attended the sex parties hosted by Yoon, for questioning. Both Yoon and Kim were banned from leaving the country.