Federal officials have started the process of clawing back thousands of dollars spent by General Services Administration workers on 2010 Las Vegas parties -- with the initial bill totaling $5,600. 

Invoices, obtained by Fox News, were sent to three top agency officials on Friday. The largest individual bill went to western regional commissioner and conference organizer Jeffrey Neely, who was ordered to repay taxpayers $2,717.09 for "wholly improper expenditures" at a party he threw. 

While the $5,600 is just a fraction of the more than $820,000 spent at the 2010 conference, the acting administrator of the agency says he's looking to see what other funds can be recovered. And lawmakers plan to press GSA to squeeze more money back from officials involved in the 2010 trip, in addition to seeking further punishment. 

Rep. Jeff Denham, R-Calif., said Tuesday that taxpayers deserve to be repaid for the expenses. He added: "Where crimes have been committed, people will go to jail." 

The House transportation subcommittee which Denham chairs held a hearing Tuesday, featuring many of the same officials who testified at a heated hearing on the House Oversight and Government Reform Committee a day earlier. Neely, who invoked his right not to answer questions at Monday's hearing, did not attend the hearing Tuesday. 

Inspector General Brian Miller and Acting GSA Administrator Dan Tangherlini both made clear Monday that further punishment could be in order. 

Miller said his office has recommended criminal charges, and is investigating possible bribery and kickbacks. Tangherlini said he'll work closely with Miller to comb through the "entire bill of particulars" to see how much GSA officials should repay.

In the wake of the inspector general's report, two officials have been fired and the administrator of the agency has resigned. Ten other officials have been placed on administrative leave. 

Robert Peck, who was fired as commissioner of the Public Buildings Service, was among the officials who received a bill for the Las Vegas trip -- along with official Robert Shepard. 

Peck, though, testified Tuesday that he was not involved in the planning of the 2010 conference, though he did attend. He called the expenses for the conference "excessive and unacceptable." 

Denham threatened Tuesday to try to dismantle the agency entirely if the excessive spending continues. 

"If we continue to not only see this type of spending, we will continue to audit. If we continue to see that you're not giving us the information on a bipartisan level to show us how these expenditures are happening, I am prepared to systematically pull apart GSA to the point where will make it a question to the American public on whether GSA is needed at all," Denham said.Â