The Environment Protection Agency's (EPA) inspector general announced Monday evening he would review employment records pertaining to Samantha Dravis, who resigned last week as the agency's senior counsel and associate director of its Office of Policy.

In a letter sent late last month, Sen. Tom Carper, D-Delaware, asked the inspector general to investigate Dravis' employment record. According to Carper, Dravis "did not attend work or perform her duties for much if not all of the months of November 2017-January 2018." Carper also wrote that he had been informed that Dravis "was likely compensated as a full-time employee throughout that time."

EPA spokesman Jahan Wilcox denied Carper's allegations last week. "Samantha Dravis has been a senior leader at the EPA and has performed her duties faithfully for her entire tenure," Wilcox told CBS News' Arden Farhi. He continued, "It is completely baseless and absurd to assert that someone with her responsibilities and office would have been away from her duties and responsibilities for months at a time, as alleged."

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But in a response to Carper released Monday night, Arthur Elkins, the EPA's inspector general, said that his office had "decided to conduct the requested review." Elkins added that while his office lacks what it considers adequate funding for its various assignments, "we have determined that the issues raised are within the authority" for his office to look into.

Late Monday, Dravis released a statement denying the allegations. "Senator Carper should be ashamed that he is responsible for the government resources that will be wasted investigating his baseless and categorically false accusations," she wrote. "I am confident that I have worked more hours and accomplished more in one month at EPA than Senator Carper has accomplished during his year-long letter-writing campaign against members of this administration. I have never been absent from work for weeks at a time, nor have I neglected my duties during the time period in question."

Dravis added that calendar records and timesheets from the period in question will show that she worked full time. Agency sources said those documents would likely be made public later this week.

"The Senate has a constitutional duty to conduct oversight of any administration, especially when presented with credible information from sources within an agency and amid numerous ethical failings on the part of its leadership," a spokesperson for Carper said in a statement to CBS News on Tuesday. "Senator Carper will continue to conduct appropriate oversight and looks forward to the outcome of the IG's investigation."

People who were in regular contact with Dravis in November, December and January confirmed to CBS News that she was in the office regularly. A source close to Dravis said she took time off around Thanksgiving and Christmas.

In December, Dravis accompanied EPA Administrator Scott Pruitt on a trip to Morocco that is now part of a separate investigation into Pruitt's first class travel costs.

Pruitt has come under scrutiny for renting a room at a favorable rate from an energy lobbyist and authorizing major raises for two young aides without clearance from the White House. Sources tell CBS News that Dravis, who had been looking to move to the private sector for some time, had no involvement in the scandals, and submitted her resignation before those stories broke.

"It has been an honor to serve in this role at EPA, and I am enormously grateful for the opportunity," Dravis told CBS News last week. "I wish Administrator Pruitt and all of the public servants at EPA the very best."

CBS News' Arden Farhi and Julianna Goldman contributed to this story.