Medicare is a national social insurance program in the United States. An audit conducted by the U.S. Department of Health and Human Services (HHS) unearthed a staggering $30 million paid by Medicare for unconfirmed ambulance rides in the first half of 2012.

Dubbed as 'mystery rides' by the federal investigators, these transports pertain to ambulance calls with no trace or evidence of medical care involved.

"[They're] mystery rides because we don't have any information in our files, in Medicare files, to show what medical service the person received, of if they received a medical service," said deputy inspector general Suzanne Murrin, who is part of the investigation team from the U.S. Department of Health and Human Services.

Part of Medicare's services is to provide ambulance rides to patients who require a trip to the hospital or to see their physicians for medical needs. These ambulance rides are beneficial to patients who do not have their own transportation or can't walk. However, surveillance videos show some ambulance riders making a stop to get take-out food.

HSS investigators explained that Medicare has been fighting ambulance fraud for a long time. In the last 10 years, the number and total cost of ambulance transports increased tremendously. In 2012, Medicare's outpatient care ambulance rides paid $5.8 billion, an amount that nearly doubled since 2003.

HHS' initial investigation first looked at the suspicious $7.3 million ambulance transports in Medicare's records. As they dug deeper, they found another $24 million of suspicious ambulance claims, later dubbed as 'mystery rides', for transports that do not have medical or hospital records to justify such claim. There has been a great deal of dubious billing for ambulance rides since 2012 and the Medicare program needs to address such weakness, Murrin added.

Medicare has placed numerous initiatives to deal with the rise of unconfirmed ambulance transports since 2012. Investigators pointed to Philadelphia and Houston as top sites for 'mystery rides'. To address the report claims, new ambulance companies from these states were recently banned by Medicare from joining the ambulance transport program. Investigators suggested that ambulance activities in the states of New York and Los Angles should also be given closer monitoring.