Washington (CNN) - A government official at the center of lavish spending at a Las Vegas conference claimed his Fifth Amendment rights against testifying before congressional hearing Monday, while his boss said she mourned her departure from public service over the controversy.

Jeff Neely, the General Services Administration official who organized the 2010 conference that cost $800,000, repeatedly refused to answer questions, saying more than five times: "I respectfully decline to answer any questions here today based on my Fifth Amendment constitutional privileges."