By HENRY C. JACKSONWASHINGTON (AP) â¿¿ An Internal Revenue Service official refused to testify Wednesday before a House committee examining his relationship with the CEO of computer services company that has as much as $500 million in contracts with the tax agency. Gregory Roseman said he was advised by his lawyer to invoke his constitutional right against self-incrimination. The House Oversight and Government Reform Committee is investigating government contracts secured by Strong Castle Inc., and whether a friendship between Roseman and Strong Castle's CEO, Braulio Castillo, was a factor in the company's ability to win such large contracts with the IRS. Beth Tucker, the agency's deputy commissioner for operations support, told lawmakers that the IRS was working to sever its ties with Strong Castle and recently referred its contracts with the company to the Treasury's inspector general for tax administration for further investigation. Tucker said Roseman, who worked in the IRS's procurement office but has since been transferred to a different department, should not have had any contacts with Strong Castle and Castillo. She said she also was troubled by other aspects of Strong Castle's work with the IRS, including allegations that Castillo took advantage of programs in the Small Business Administration and the Department of Veterans Affairs to move to the front of the line for IRS contracts. "Let me be clear, the information that we've seen about the personal relationship with Mr. Roseman and Mr. Castillo is inappropriate," Tucker said. "Mr. Roseman should have recused himself immediately." The committee, which has been investigating ties between the IRS and Strong Castle since February, released a report Tuesday that detailed Castillo's relationship with Roseman. Strong Castle, which was founded just two years ago, scooped up more than a dozen contracts with the IRS in 2012 for computer services potentially worth hundreds of millions of dollars.