Raj Rajaratnam, founder of the Galleon hedge fund group at the heart of an insider trading scandal, on Tuesday attacked prosecutors’ use of court-authorised wiretaps as a violation of his constitutional rights and questioned the credibility of a key witness. Rajaratnam also denied using inside information to make investments, according to court documents filed in response to the SEC which, along with federal prosecutors, filed civil and criminal insider trading charges against him and five others last month.