Rajbir Singh Ghuman, OSD to Punjab Chief Minister Bhagwant Singh Mann, was quizzed by the CBI again on Tuesday. His questioning at the CBI office here lasted for over four hours.Rajbir, while interacting with mediapersons after his questioning, said the CBI sleuths asked nearly 100 questions and he answered all of them. “The CBI is being used by the political masters in Delhi to hit out at the CM. Mann is the most honest CM ever and they are trying to defame him and his office by embroiling me in this case,” he said.Rajbir was booked by the CBI along with five others in a case of corruption and influence peddling in the Chief Minister’s Office. Today was the fifth time he was summoned and has now been called for questioning again on October 31. Meanwhile, Rajbir has sent a legal notice for defamation to Akali leader Bikram Singh Majithia.