A registered nurse and nurse practitioner who fraudulently billed commercial health insurers and Medicare nearly $4.4 million for services that he falsely claimed to have provided to patients in Rhode Island, New York, and Florida, pleaded guilty on Wednesday in federal court in Rhode Island to an eleven-count information charging him with fraud, mail fraud, aggravated identity theft, and causing the introduction of misbranded drugs into interstate commerce. Alexander A. Istomin, 56, admitted that he routinely submitted fraudulent claims for in-person patient services that he falsely claimed to have performed at his offices in Rhode Island, New York, and Florida. In some instances, the patients that Istomin claimed he met with in person were out of the country at the time of the alleged visits. On many other occasions that he claimed to have been seeing patients, Istomin himself was either in a different state or another country, often times in Russia. The investigation also determined that the supposed office that Istomin maintained in East Greenwich, and to which he had some payments mailed, was a non-existent medical practice at which no medical services were provided.