PROVIDENCE, R.I. (AP) — A nurse practitioner who defrauded health insurers and Medicare out of nearly $12 million by seeking payments for patient services that were never performed has been sentenced to seven years in prison.

Alexander Istomin, 57, submitted fraudulent claims for in-person patient services that he falsely claimed to have performed at offices in Rhode Island, New York and Florida, the U.S. attorney’s office in Rhode Island said in a statement Wednesday.

In some cases, patients that Istomin claimed to have met in person were in another country at the time. Some visits took place at a ghost office in East Greenwich, Rhode Island, that Istomin claimed was part of his medical practice when it was used solely for the purpose of receiving mail, prosecutors said.

He also used patient names and other information to get prescriptions filled, which he would keep and then distribute to others, prosecutors said.

He also waived copayments for some Medicare patients, which is prohibited, and in return the patients would not report the fraudulent billing, prosecutors said.

Eight insurers were affected, prosecutors said.

He pleaded guilty in October to health care fraud, mail fraud, aggravated identity theft, and causing the introduction of misbranded drugs into interstate commerce.