Michael Jackson’s private physician, Dr. Conrad Murray, was sentenced to four years in jail Tuesday for his role in the singer’s 2009 death, but so far he hasn’t been pushed out of the Medicare program.

According to a letter two senior Republicans on the Senate Finance Committee sent to Medicare’s administrator on Tuesday, Murray and other convicted felons and unlicensed physicians are still listed as legitimate physicians on the health plan’s provider database, pointing to a serious vulnerability that leaves the program open to fraud and could put seniors at risk.

Conrad’s case “illustrates Medicare’s failure to act in the best interest of seniors,” wrote Sens. Orrin Hatch, R-Utah, and Tom Coburn, R-Okla, in the letter to Health and Human Services Secretary Kathleen Sebelius. A spokesman for the Centers for Medicare and Medicaid Services had no immediate comment.

Murray’s case is a high profile example of Medicare’s failure to remove convicted felons and doctors who have lost their medical licenses from the program, an issue highlighted earlier this year by iWatch News. In Murray’s case, California suspended his medical license in January. In November, Murray was convicted of involuntary manslaughter. Yet Murray is still listed as a Medicare provider in the CMS internal database. “Despite the national media coverage of Dr. Murray’s conviction, he remains a legitimate Medicare provider,” Hatch and Coburn wrote in the letter.

Jackson’s doctor is not an isolated case. In the letter to Sebelius, the senators reference an Ohio physician who continues to have a valid Medicare provider number despite a conviction for conspiracy to commit murder, as well as physicians who have been convicted of tax evasion, health care fraud, drug distribution and “lewd and lascivious behavior.” The letter does not name the physicians.

Tuesday’s letter is not the first time the senators have sounded the alarm about felons in Medicare. In September, the senators sent a letter to Dr. Donald Berwick, CMS’s outgoing administrator, listing 34 doctors and other providers who were convicted of a felony or pleaded guilty but retained their Medicare privileges. In November, Berwick responded by letter, and said in many of the cases, Medicare lacks authority to exclude the providers because they were convicted on non-excludable offenses, including felony drunk driving charges and hunting violations.

In response Tuesday, the senators called Berwick’s response troubling, since he pointed to the exceptions. Lack of communication between CMS and federal law enforcement agencies may be one cause of the felon problem. In Tuesday’s letter to Sebelius, the senators expressed exasperation that CMS does not have data sharing agreement to share felony indictment and conviction data with the Department of Justice, the Internal Revenue Service, state agencies, and even with its own Office of Inspector General.

“In a time of increased technological capability,” they wrote, “it appears CMS is disconnected. Without data sharing agreements with its law enforcement partners, we fear CMS will remain in the dark and Medicare beneficiaries will be placed at risk.”