Washington (CNN) -- Top Republicans investigating the botched "Fast and Furious" gun-running sting have demanded that the Bureau of Alcohol Tobacco, Firearms and Explosives explain why an official at the center of the controversy remains a government employee while apparently working for a top financial firm.
Sen. Charles Grassley, R-Iowa, and Rep. Darrell Issa, R-California, wrote to Acting ATF Director Todd Jones complaining the arrangement for "double dipping" in the case of William McMahon is "not the culture of change that you promised to bring to ATF."
The letter from Grassley and Issa said that McMahon, the agency's former Deputy Assistant Director for Field Operations, has been allowed to take extended paid leave to enable him to reach retirement eligibility while working as head of global security for JP Morgan in the Philippines.
The lawmakers faulted McMahon for failing in his official post to properly supervise the activities of the agency's Phoenix office, which ran "Fast and Furious." They also blamed him for "his admitted failure to read important documents he was responsible for authorizing and his false testimony regarding his role in authorizing applications for wiretaps in the case".
The conclusions were included in their latest staff report on the case in July.
"Fast and Furious" attracted congressional scrutiny for allowing illegally purchased weapons to be smuggled into Mexico from Arizona. In the botched sting, more than a thousand weapons were lost and ended up with Mexican drug cartels. The controversy exploded when two of the lost weapons were found at the scene of the killing of U.S. Border Patrol agent Brian Terry in Arizona.
The ATF confirmed on Wednesday that it had received the correspondence.
"We are reviewing the letter, and will respond," said Drew Wade, an agency spokesman.
Wade said McMahon remains an ATF employee but is on leave. He declined to provide other details but the Grassley/Issa letter said that a senior ATF official confirmed McMahon's employment status last week.
The lawmakers called it an "unusual arrangement" that came about recently. They said McMahon's leave apparently would last about four or five months and allow him to begin his second career before officially separating from the government.
JP Morgan could not immediately be reached for comment.
Grassley and Issa gave Jones until September 4 to answer more than 20 questions about McMahon's employment status.
The Justice Department inspector general is believed to be close to completing an investigation of "Fast and Furious." Attorney General Eric Holder has been awaiting the report to determine what actions to take against individuals involved in the case.
Holder promised Congress that such "gun walking" of weapons into Mexico would never again be allowed. The House found Holder in contempt in June for refusing to fully comply with requests for information about "Fast and Furious" sought by Issa's committee.