A New England anesthesiologist stands high above all others in Medicare’s recently released list of how much money it pays providers, and court records help explain why he posted Ruthian numbers in a league of mostly singles hitters.

According to records the Centers for Medicare & Medicaid Services (CMS) made public in April, the anesthesiologist, Fathalla Mashali, MD, billed Medicare $3.47 million in 2012. The total is twice that of the anesthesiologist who came in second place. Of the 32,641 providers who appear on the list, only nine in the United States billed Medicare more than $1 million that year.

Dr. Mashali, who owns pain management clinics in Massachusetts and Rhode Island, is facing nine federal counts of both health care fraud and aiding and abetting fraud. He was arrested at Boston’s Logan International Airport in February while attempting to travel to his native Egypt, carrying with him a job reference letter signed by his nephew, who is a doctor based in Michigan. According to court documents, the letterhead was from a health care clinic in Hawaii, where the nephew never lived or worked.

A grand jury returned an indictment against Dr. Mashali in March. In April, U.S. Magistrate Judge Leo Sorokin deemed Dr. Mashali a flight risk and ruled that the clinician may be freed on $5 million bond secured by property he, his wife and children own, and that he must remain at his home in Dover, Mass., and wear an electronic monitor.

With a fraud investigation pending but before his arrest, Dr. Mashali in 2013 surrendered his licenses to prescribe controlled substances both in Massachusetts and Rhode Island.

The indictment alleges that Dr. Mashali’s scheme to defraud Medicare lasted from October 2010 to March 2013. “I cannot comment on any connection at this time” between the indictment and the Medicare billing list, said Christina Sterling, a spokeswoman for the Justice Department’s Boston office. She instead referred a reporter to documents related to his arrest.

“I don’t think there’s any relationship between the indictment and the amount of money he billed Medicare,” said Dr. Mashali’s attorney, Jeffrey Denner of Boston. When asked why Dr. Mashali billed Medicare substantially more than any other anesthesiologist in the country, Mr. Denner explained that his client had many patients across two states. He noted that Dr. Mashali also performed many lab tests and “processes a lot of data.”

Medicare records show that Dr. Mashali was reimbursed hundreds of thousands of dollars for tens of thousands of assays, but the indictment does not mention lab testing as part of the alleged fraud.

When all the work is tallied, “you’ll find that it’s not an extraordinary number at all,” Mr. Denner said. He would not make the doctor available for comment.

Dr. Mashali, 59, who received his medical degree from Kasr El-Aini School of Medicine in Cairo, owned and operated New England Wellness and Pain Management, Inc., also known as New England Pain Associates (NEPA), which had three clinics in Massachusetts and one in Rhode Island. He had a license from the Drug Enforcement Administration to dispense narcotics.

Health care providers doing business with Medicare submit bills for their patients using one of five evaluation codes for office visits, depending on the complexity of the visit and time spent with the patient. The codes cover time limits from between five and 25 minutes; the more time spent with a patient, the higher the bill to Medicare.

Norman Dozier, MD, who operates a pain clinic in Abilene, Texas, billed Medicare for $1.17 million in 2012, according to the records—good for fifth place nationwide on the anesthesiology list. “I don’t know how a person can possibly receive more patients than I do,” he said. Dr. Dozier employs a physician assistant, but otherwise “I’m by myself,” he said. “I’m very, very busy. I see 60 patients, five days a week. Our population is 60% Medicare. Some of these people come [from] 100, 120 miles away.”

Flood of Data

Medicare released the records on payments after a prolonged standoff with the Wall Street Journal, which had filed Freedom of Information requests for the data.

The records show that Dr. Mashali, who was the only physician at his clinics until 2013, conducted 7,086 office visits with Medicare patients alone at his clinics. According to an affidavit signed by FBI Special Agent Clayton Phelps, former NEPA employees said that the anesthesiologist “would sometimes see up to 150 patients per day. Patients waited hours to see Mashali, not only because so many patients were booked in one day but also because Mashali regularly arrived to work between 11 a.m. and noon.” He often booked four patients to a single appointment slot.

The indictment further alleges that Dr. Mashali trained nurses and physician assistants (PAs) to bill Medicare for detailed (and more expensive) examinations when those services were not provided. Former workers approached authorities in 2012.

Briefest of Visits

A former PA told FBI agents that Dr. Mashali would often spend no more than two or three minutes with patients, usually in an office instead of a room with medical equipment and without the patient changing clothes. He also would change the Medicare code on a patient’s record to reflect “a more fulsome examination than actually occurred,” according to the affidavit. The PA confronted Dr. Mashali, who insisted he had done a thorough examination, and the PA “replied that she had never even seen him wear a stethoscope around his neck.” The next day, Dr. Mashali removed the PA from seeing patients, switching her to desk work. He also started wearing a stethoscope.

Another PA asserted that Dr. Mashali “regularly told her to hurry up and keep printing prescriptions for him to sign to keep the patients moving forward,” the affidavit said.

The affidavit states that Dr. Mashali sent Medicare 27,283 total claims in the first half of 2012 for a total of $4.8 million (the figures depart substantially from Medicare’s total, which was for the entire year), a 588% increase over the last six months of 2011.

Mr. Denner said that lab work and repayment for drugs Dr. Mashali administered take up a substantial amount of the billing. He added that Medicare never questioned the invoices. “If they felt that this was not appropriate, given that the number was so big, then they would have done something,” he said. “They don’t want to spend money they don’t have to.”

Calls to the press office at CMS were not returned. The indictment said that Medicare has the right to reject claims, but does not always do so—at least until after a provider has been paid. “Medicare presumed the truth of each claim,” the indictment said. “In other words, Medicare entrusted their enrolled providers to only submit claims for the services that they actually performed.”

Theresa Hill, a spokeswoman for the American Society of Anesthesiologists, said infractions like the ones alleged against Dr. Mashali are usually left to state medical boards. Calls and emails to several members of the society’s Committee on Professional Affairs were not returned.