Pruitt came to Washington already a controversial figure, and since taking the helm of an agency he once battled, he has faced a series of inquiries and bruising accounts of his conduct in office and use of official resources.
At the same time, Pruitt worked to carry out key elements of President Donald Trump's agenda, overseeing a rollback of Obama-era environmental regulations on climate change and pollutants. But all the while, he has been caught up in a series of unfolding controversies over everything from first-class travel to security expenses and a decision to rent a room in Washington tied to an energy lobbyist.
Ultimately, Pruitt resigned July 5 as the controversies mounted.
Here's a look at the controversies and allegations Pruitt has become embroiled in during his time in the administration:
The EPA inspector general is probing Pruitt's travel practices. The review began following reports Pruitt would frequently travel home to Oklahoma on the taxpayers' dime. The IG twice expanded the probe, first as the agency acknowledged Pruitt used both a private plane and military jet to travel four times instead of flying commercial -- at a price of $60,000 -- and again to include all of Pruitt's travel from 2017.
In February, questions over Pruitt's travel prompted House Oversight Committee Chairman Trey Gowdy, a South Carolina Republican, to announce an inquiry into Pruitt's practices, and in response to the committee's request for documents, the EPA did not appear to turn over travel waivers granted to Pruitt for first-class travel.
Pruitt defended his first-class travel in February by saying it was for security purposes, citing the "toxic environment" in politics and implying he was less likely to face threats in a first-class crowd. EPA memos obtained by CNN said that if Pruitt flew coach, the occasional "lashing out from passengers" could "endanger his life."
EPA documents reviewed by CNN in February showed attorneys for Pruitt's office justifying a series of charter flights last summer, including some $14,000 expended on travel around his home state of Oklahoma.
A report from The Washington Post in mid-March said documents the EPA provided to Congress outlined further travel expenses from Pruitt, totaling about $68,000 and including a nearly $20,000, four-day trip to Morocco and a series of first-class flights.
Staff accounts, security detail, personal errands
The Washington Post and The New York Times reported on a pair of top Pruitt aides who spoke with House Oversight Committee investigators in June. The two detailed how Pruitt enlisted them for personal tasks, including attempting to find a job for his wife with the Republican Attorneys General Association, and the Post report said both aides told the investigators about Pruitt pressing to travel first class or by private plane.
Millan Hupp, a Pruitt staffer, told the House Oversight Committee that she helped search for rental properties for Pruitt and his wife. Hupp also said she reached out to the Trump International Hotel in Washington after Pruitt said he thought there was "an old mattress that he could purchase" from the President's hotel. Government ethics experts said the rental searches might have clashed with ethics rules. Hupp resigned in June.
Kevin Chmielewski, a former deputy chief of staff for operations for Pruitt, told The Hill that Pruitt had not reimbursed Sydney Hupp, a scheduler who has since departed EPA and is Millan Hupp's sister, for a $600 hotel bill she paid for personally, and that Pruitt's chief of staff reimbursed her in cash. The Washington Post, citing a current and former EPA officials, said Pruitt "routinely" had staff put reservations for him on their credit cards.
Emails the Sierra Club obtained through a Freedom of Information Act request showed Sydney Hupp reached out to the CEO of Chick-fil-A about the possibility of Pruitt's wife becoming a franchise owner. Pruitt later said he and his wife "love" the fast-food chain and praised it as "a franchise of faith."
The Washington Post reported in early June that Pruitt had enlisted his security detail to run a series of personal errands, including driving him around to find a lotion from Ritz-Carlton hotels. The Daily Beast, citing four sources, said Pruitt sent out staff regularly to pick up snacks for him.
Democratic Sen. Sheldon Whitehouse sent a letter to the inspector general of the EPA that said Pruitt's constant security included even personal trips to Disneyland and the Rose Bowl. House Democrats wrote a letter in June following up on the Rose Bowl tickets, asking the source of the tickets, the head of a PR firm that represents oil and gas companies, how the tickets were requested and how many Pruitt had received.
The Environmental Integrity Project obtained heavily redacted documents from the EPA that showed the agency spent more than $30,000 on security for Pruitt's 2017 trip to Italy.
A letter from EPA's inspector general in May said Pruitt had requested a full 24/7 security detail as soon as he was confirmed to his job leading the agency. The finding contradicted earlier claims by Pruitt and EPA about his security detail being needed due to threats against him.
Sen. John Barrasso, the Wyoming Republican who leads the Senate committee overseeing EPA, has asked Pruitt to provide a list of the agency email accounts he uses after Senate Democrats said they believe Pruitt uses four email accounts and were unsure if the agency searches all four accounts when asked to produce public records.
EPA is fighting a lawsuit from Public Employees for Environmental Responsibility that alleges the Pruitt administration is deliberately avoiding creating written records of meetings and decisions (so that there are no documents subject to leaking or FOIA) and that Pruitt "uses phones other than his own to deal with important EPA-related matters so the calls do not show up in his call logs."
Rep. Elijah Cummings of Maryland, the top Democrat on the House Oversight Committee, issued a letter in June accusing Pruitt of directing EPA to prevent or delay public records requests.
Chmielewski told CNN that Pruitt and his aides kept "secret" calendars and schedules and decided which meetings or calls with industry representatives and others to include on the publicly available calendar.
Pruitt lived for about six months in a Capitol Hill condo owned by a health care lobbyist whose husband has lobbied EPA, and paid below the market rate, according to reports by ABC News and Bloomberg. A former deputy chief of staff told congressional investigators the energy lobbyist, J. Steven Hart, called Pruitt's chief of staff to complain that Pruitt was behind on rent, and a separate source told CNN the couple eventually evicted Pruitt by changing the condo lock code. CNN has reported that White House officials are exasperated by the housing controversy.