The police in Poland were investigating allegations criminals have bribed doctors to give them fake cancer diagnoses to get early release from prison.
Initial investigations showed dozens of criminals have been freed from prison under the scam.
Ananova.com says between 2000 and 2005, the Gdansk prison set free criminals on compassionate ground after corrupt prison doctors were reportedly paid thousands of dollars.
It says the scam was so sophisticated that in some cases criminals actually went operations where the tissue of real cancer victims were substituted and presented as evidence.
Police say prisoner were then ordered chemotherapy so they could be released.
A tipster told the police of the scam.
