WASHINGTON — The federal General Services Administration has handed out more than $1 million in taxpayer-funded bonuses since 2008 to dozens of employees who were under investigation for misconduct.

Already under fire for its lax oversight of spending, the GSA gave bonuses to at least 84 of its employees while they were being investigated, according to a Senate analysis. Some were as low as several hundred dollars, while one employee received nearly $76,000 over five years.

The number of employees who received the bonuses while under investigation by the GSA’s inspector general could be even higher. Information related to some of its current work isn’t yet available, including an examination of a lavish conference in Las Vegas three years ago that outraged lawmakers and led to the resignation of agency administrator Martha Johnson and the dismissal of two of her deputies in April.

The GSA, which oversees the business of the federal government and is its landlord and contracting officer, is still facing questions over the nearly $1 million Las Vegas event, which featured $7,000 worth of sushi rolls, a mind reader for entertainment and $20,000 worth of gift iPods. Employee airfare to the conference alone cost $147,000.

Testifying on Capitol Hill in April about the conference, GSA Inspector General Brian Miller said, “Every time we turned over a stone we found 50 more with all kinds of things crawling out.”

To critics, the revelation of the bonuses represents yet another example of a less-than-rigorous approach to fiscal responsibility.

U.S. Sen. Claire McCaskill, a Missouri Democrat who chairs the Senate Subcommittee on Contracting Oversight, said the agency had a “culture of entitlement,” particularly among senior managers, that rewarded “bad judgment.”

“It’s the process that’s disturbing,” she said. “We don’t have a policy in place that says if employees are under investigation, at a minimum you need to withhold bonuses, and the finding of that investigation is relevant to the awarding of the bonuses.”

GSA spokesman Adam Elkington said the agency was conducting a “top-to-bottom review” of how it operated.

“This comprehensive review includes all bonus payouts in recent years, especially for those individuals under investigation by GSA’s inspector general,” Elkington said.

Inspectors general assigned to federal agencies look into issues concerning waste, fraud and abuse, as well as adherence to government rules and policies.

Many of the bonuses that the 84 GSA employees received were in the neighborhood of $2,000 to $5,000, but some were much higher. They received an average of eight bonuses. Each was an award for individual or group performance, or some other special recognition.

For example, a regional commissioner for the GSA’s Public Buildings Service received annual bonuses of $18,000 and $16,500 in fiscal years 2010 and 2011, respectively, and nearly $10,000 this year. Including annual bonuses the same employee received while holding a different position in fiscal years 2008 and 2009, the worker collected more than $76,000 in extra GSA income over the five-year period.

Another GSA employee, a program operations officer, received annual bonuses of nearly $8,000 for five straight years even though the officer had been reassigned after an inspector general investigation related to the abuse of authority.