(CBS News) Rep. Darrell Issa, chair of the House Oversight and Government Reform Committee, said Jeff Neely, the General Services Administration (GSA) official allegedly involved in a costly Las Vegas conference, must appear before the committee on Monday.
Neely's attorney, Preston Burton, sent a letter to Issa saying Neely planned not to attend because he would "assert his constitutional privilege to remain silent."
In a responding letter, Issa wrote, "I write to advise that the subpoena you accepted on Mr. Neely's behalf remains in effect."
Issa initially issued a subpoena to Neely to appear at Monday's hearing with five other witnesses, including the GSA's Inspector General and the agency's former administrator, Martha Johnson, who resigned after the scandal was made public.
Neely was put on administration leave for overseeing a conference for 300 GSA employees at a Las Vegas-area resort that cost $822,751, which the Inspector General called "excessive, wasteful and in some cases impermissible."
Inspector General Brian Miller has recommended the Justice Department open an investigation, according to the Washington Post.
"Mr. Neely is uniquely qualified to answer questions," Issa wrote in the letter. "He has been invited to appear with the expectation that his testimony will advance the committee's investigation of wasteful spending by GSA."