A spokesman for A.M.I. also declined to comment on Mr. Perrotta’s assignments, but did not challenge that the company had worked with him. It is unclear when he began working with A.M.I. or how he first came into contact with the company.
Mr. Perrotta has been at the center of intense criticism of Mr. Pruitt for deploying expensive security measures at the E.P.A. He was named chief of the administrator’s security detail when his boss was removed after resisting Mr. Pruitt’s requests, such as using lights and sirens to cut through traffic during trips around Washington, including to restaurants.
Mr. Perrotta’s relationship with Mr. Pruitt is expected to be a subject of questions on Thursday, when the E.P.A. administrator is scheduled to appear before two separate House committees.
In an email to The Times, Mr. Perrotta said he was being unfairly attacked.
“I was a highly respected federal agent,” said Mr. Perrotta, 50, who worked in the Secret Service before joining the E.P.A. in 2004 and made his name investigating the Gambino crime family for the Bronx district attorney.
He said recent news coverage of his role in Mr. Pruitt’s E.P.A. had “tarnished” his image. “I am retiring as planned,” he wrote, referring to his intended departure from the agency this summer, “but has anyone mentioned that I served with honor and distinction the Obama Administration? I served two former Administrators and now to end my career this way is totally unacceptable.”
During the 2016 campaign, Mr. Perrotta was assigned to the security detail protecting Gina McCarthy, who served as the head of the E.P.A. from 2013 until the end of the Obama administration. Liz Purchia, a spokeswoman, said Ms. McCarthy was not aware of the work Mr. Perrotta did for A.M.I.
Two E.P.A. employees who served on security details with Mr. Perrotta in recent years also said they did not know about his outside work. In 2013, Mr. Perrotta founded a consulting firm, Sequoia Security Group.
On Tuesday, two Democratic senators sent a letter to the E.P.A.’s Office of General Counsel asking questions about the nature of Mr. Perrotta’s outside work.
In the letter, the senators — Thomas R. Carper of Delaware and Sheldon Whitehouse of Rhode Island — suggested that Sequoia offered a range of services that appeared to be outside the scope of the waiver Mr. Perrotta received in 2013.
Among the services advertised on the firm’s website are “the collection and analysis of intelligence and media investigations” and “executive protection.”
The two-page waiver from the E.P.A. only specifically cleared Mr. Perrotta to operate “a security firm that will provide cybersecurity and denial of service insurance to consumers.”
The letter from the senators also asked the E.P.A. to provide copies of any financial disclosure statements filed by Mr. Perrotta detailing his outside income.
Representative Trey Gowdy, Republican of South Carolina, who is chairman of the House Committee on Oversight and Government Reform, has separately asked him and four other top aides to submit to a “transcribed interview” with investigators about the security detail and Mr. Perrotta’s firm.
Mr. Perrotta set up his security consulting business, based in Maryland, to prepare for life after leaving the federal government, he has told associates. They said he planned to retire from the E.P.A. in July. Last month, he requested and received an extension of the outside-work waiver for another year, according to people familiar with the waiver.
Mr. Perrotta has been registered as both a Republican and a Democrat, according to voter records, and associates say he has described himself as fiscally conservative and socially liberal.
He is acquainted with an important gatekeeper for the president — Keith Schiller, who served as Mr. Trump’s longtime bodyguard and later as his head of Oval Office operations — as well as a top executive at Mr. Trump’s company, Matthew Calamari. Mr. Perrotta offered them advice on security for Mr. Trump’s Washington hotel, which is across the street from the E.P.A.’s headquarters, but was not paid, according to people who know the men.
Mr. Perrotta’s associates say his outside work seems to be motivated by a desire to be at the center of the action and to make money, rather than by politics.
“I’ve never heard him make a disparaging comment about either party,” Edwin Steinmetz, a business partner, said earlier this month. Pointing out that Mr. Perrotta has worked for both Republicans and Democrats, Mr. Steinmetz said, “You either get in line and follow protocol, or you find a new job.”
Mr. Steinmetz conducted a security sweep of Mr. Pruitt’s office last year, and the E.P.A.’s inspector general is investigating Mr. Perrotta’s role in steering the $3,000 contract to him. The money was paid to Mr. Steinmetz’s firm, Edwin Steinmetz Associates, according to an invoice, and Mr. Steinmetz said that Mr. Perrotta did not receive any compensation for the work. Mr. Steinmetz is also listed as a company official on the Sequoia website.
Mr. Steinmetz did not find any listening devices in Mr. Pruitt’s office, according to documents from the E.P.A.’s homeland security division. The documents indicate that the sweep was “very basic and cursory” and “did not employ the equipment, proper certification, or necessary processes” required by the federal government for sweeps of sensitive facilities.