Clinton again publicly declared that he never had sexual relations with her, but Starr produced a set of tapes indicating that he had. Linda Tripp, a colleague of Lewinsky's, had made numerous recordings of conversations when the two of them had been friends working together at the Pentagon. The tapes also implied that Clinton urged Lewinsky to lie about their affair. A flurry of stories emerged in the media questioning motives and probing into the characters of both women. Starr plugged away, calling Lewinsky's mother to testify against her daughter in a move that was heavily criticized and did nothing to increase sympathy for the prosecution. Sordid details were revealed in the press, from the particular sex act that Clinton and Lewinsky supposedly engaged in, to rumors that she owned a dress that was stained with presidential semen (subsequent testing of the garment proved no such substance). Starr even obtained bookstore receipts revealing the young woman's choice of reading materials. He called on White House aides and Secret Service personnel to testify against the president and requiring Lewinsky to submit fingerprints and handwriting samples. Critics sniped at Starr continuously throughout the investigation. Early on, his detractors accused him of partisanship; this peaked in early 1998 when First Lady Hilary Rodham Clinton publicly charged him with being part of a right-wing conspiracy against her husband. Then, some took him to task for continuing his private work while pursuing Whitewater. Even though it was not illegal, many believed it was improper and unusual and came very close to being a conflict of interest. Starr, it was noted, had been representing big-business clients, such as General Motors, Brown & Williamson tobacco company, Southwestern Bell Telephone, and the NFL Players Association. Others complained that well over $30 million and close to four years had been spent on investigating a popular president, without proving any wrongdoing on his part. As the Whitewater case dragged on for years, the complaints grew louder. The investigation reached a critical point in the summer of 1998 when Starr submitted a lengthy report to Congress, which was made available to the public over the Internet and in book form. Tapes of the president's grand jury testimony regarding his relationship with Lewinsky were soon made public as well. Though Clinton did not admit, technically, to having sexual relations with Lewinsky, he revealed that he had an "improper relationship" with the intern, who was 21 years old when the incidents began.