Republican lawmakers allege in a letter to Attorney General Eric Holder that a key figure in the failed Fast and Furious anti-gunrunning operation has been allowed to earn a second paycheck while still receiving his government salary.
The new allegations come as Holder reviews the long-awaited internal report detailing what happened in -- and who is to blame for -- Fast and Furious, in which the U.S. knowingly let some 2,500 weapons slip into the hands of the Sinaloa Cartel in Mexico, failing to track the guns as planned. 
Sources tell Fox News the Office of Inspector General delivered the report to the Department of Justice on Tuesday. Under existing protocols, the department has a month to respond to the report's findings, after which, the inspector general typically releases the document to the public.
Meanwhile, Sen. Charles Grassley and Rep. Darrel Issa, the two Republicans leading the charge against Holder on Capitol Hill, claimed in a letter Tuesday that ATF Assistant Deputy Director Bill McMahon has received a leave of absence allowing him to pull down two salaries. Taxpayers pay him six figures to do his ATF job while he's also reportedly pulling down in excess of $100,000 as the full-time director of global security and investigations for JP Morgan in the Philippines.
The arrangement allows McMahon to retire in December with a full government pension.
Records show McMahon approved Fast and Furious and supervised it as director of western operations. In July 2011, before a Congressional Committee, he apologized for his mistakes.
"As the ATF senior executive of the West Region, I share responsibility for mistakes that were made in the Fast & Furious investigation," McMahon said. "The advantage of hindsight, a thorough review of the case, clearly points me to things that I would have done differently."  
Issa, Grassley and some agents inside the ATF are livid over the special treatment given McMahon. They say personnel codes 
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