Jeffrey Neely, who is at the center of a congressional probe into the spending scandal at the General Services Administration, or GSA, has asserted his right to remain silent while former administrator Martha Johnson apologized for spending $823,000 at a Las Vegas conference in 2010.

Neely, who was subpoenaed to appear before the House Oversight and Government Reform Committee on Monday, has been placed on leave as a regional executive in Western states. This committee's hearing is the first of four that will look at the culture of overspending at the GSA. The overspending was brought to light in a report by the agency's inspector general Brian Miller.

I personally apologize to the American people for the entire situation, Johnson said. As the head of the Agency, I am responsible. I deeply regret that the exceedingly good work of GSA has been besmirched.