The letter from Inspector General Arthur A. Elkins Jr. says that his office will look into "whether the EPA complied with applicable oversight controls in deciding to make the expenditures" to add security to Pruitt's security detail.
CNN learned in October
that the EPA was beefing up security measures surrounding Pruitt to an unprecedented level, and members of Congress began to ask if the costs are a "potential waste or abuse of taxpayer dollars."
Pruitt's security detail was in the process of hiring a dozen more agents, a source with knowledge of the situation told CNN then, as the number of threats against the agency leader increased. The incoming agents were intended to grow the team that works in shifts to provide him around-the-clock protection, something unheard of for Pruitt's predecessors.
Pruitt's travel spending has also come under scrutiny in recent months
following news reports outlining frequent trips to his home state of Oklahoma as well as several flights on charter and government aircraft. Earlier this week, the EPA Office of Inspector General announced it is expanding the time frame of its probe into Pruitt's travel. Previously, the investigation was looking at travel through September 30, 2017, and will now include travel through December 31 "based on additional congressional requests."
Previous EPA administrators, whose public profiles and security arrangements are typically smaller than other members of the Cabinet, haven't had anywhere close to the level of security being assembled for Pruitt. (CNN has withheld specific details about the size of Pruitt's security detail.)
Sen. Tom Udall, D-New Mexico, has asked the EPA for additional information about the detail, including an accounting of costs and whether the increased security measures might be pulling resources away from enforcement programs.
The EPA's Criminal Investigation Division is providing Pruitt's 24/7 security detail, a labor-intensive responsibility that has resulted in special agents being pulled from their regular posts investigating environmental crimes.
These agents are armed federal law enforcement officers who typically investigate cases such as the dumping of hazardous waste, improper disposal of dangerous substances like asbestos, and pollution of drinking water. Some are former FBI agents.
The inspector general's office said it has been asked to investigate whether Pruitt's security detail is a proper use of environmental enforcement officers, and whether the practice detracts from the agency's mission of cracking down on environmental crimes.
No previous EPA chief has ever received a 24/7 security detail, the agency's inspector general said. Two prior administrators were guarded primarily when traveling.
The EPA's inspector general's office, which investigates threats, says Pruitt has received more death threats than any of his predecessors. The office has launched more than 70 investigations into threats against Pruitt and others, the agency said.
Last year, the Trump administration announced plans to cut the agency's 2018 budget by 30%
, including major cuts to the agency's enforcement work and staffing as well as the elimination of some programs.