The General Services Administration has come under fire from congressional critics who are decrying questionable bonuses and travel expenses.

Since 2008, the GSA has given more than $1 million in bonuses to 84 employees under investigation by its inspector general, according to details released Monday by the office of Sen. Claire McCaskill (D-Mo.).

An unnamed program officer received $38,664 in bonuses during an investigation. That employee was later reassigned because of allegations of abuse of authority. A supervisor who was reprimanded for interfering in an inspector general’s investigation received more than $20,000 in bonuses, according to McCaskill’s office.

While the GSA does not prohibit bonuses to employees under investigation, McCaskill questioned the actions.

“It doesn’t pass the smell test to be awarding huge bonuses in taxpayer dollars to officials who are being investigated or have already been found responsible for fraud and waste of those very taxpayer dollars,” she said in a statement.

“As previously stated, GSA is conducting a top-down review of our agency’s operations,” said GSA spokesman Adam Elkington. “This comprehensive review of our agency operations includes all bonus payouts in recent years — especially for those individuals under investigation by GSA’s inspector general.”

In April, the GSA’s inspector general released details of an $823,000 employee conference in Las Vegas. Inspector General Brian Miller was so concerned about his findings that he offered an interim briefing to senior GSA leadership.

During a congressional hearing in April, former administrator Martha Johnson explained that she was advised by the inspector general’s office not to take personnel action until the report was finalized. Johnson resigned in the wake of the spending scandal, and two of her deputies were fired.

Jeffrey E. Neely, the public buildings commissioner for the Pacific Rim region, who organized the conference, received $9,460 in bonuses for 2011. He was one of a number of employees put on administrative leave. Recently, the GSA reported that he had left the agency.

In another issue drawing lawmakers’ attention, the House Oversight and Government Reform Committee last week released details about 95 high-ranking GSA employees who were assigned to work from home but racked up $750,000 in travel expenses over nine months.

According to e-mails and other documents provided to the House panel, which oversees the federal workforce, Neely said he was surprised by the travel expenses.

“OMG,” he wrote in an October e-mail to Regional Public Buildings Service Commissioner Robin Graf, who had sent a spreadsheet with a breakdown of the travel reimbursement costs for “virtual” employees. She expressed concern about a lack of oversight.

“100 virtuals and most of them with some pretty serious grades,” Neely wrote, referring to the employees’ General Schedule status. “Well this is a fine mess we’ve gotten ourselves into.”

Neely forwarded the e-mail chain to other colleagues with this message: “This will take your breath away. Don’t share further.” The work-from-home employees were apparently traveling to regional headquarters in the Public Buildings Service and elsewhere.

Oversight Committee Chairman Darrell Issa (R-Calif.) wrote a letter Friday to acting GSA Administrator Dan Tangherlini expressing concern about the latest travel expenses to emerge.

Issa asked for further documentation of the trips, as well as justification for work-at-home arrangements and whether they are effective.