The head of an Athens hospital said yesterday that an investigation into how pieces of rat ended up in food served to patients last month indicates that someone may have deliberately placed the diced rodent parts into a cooking pot. Investigators at the Greek School of Public Health discovered that someone had cut up the rat with a knife, said Orestis Schinas, president of the Dromokaitio mental hospital in Athens. But the investigators’ findings were not entirely conclusive. Health authorities left open the possibility that the rodent may have been alive when it fell into a boiling soup pot. The 26 workers questioned by investigators said it would have been impossible for the rat to have been in the soup during preparation or serving, suggesting the pieces of the rodent were thrown into the food at a later stage. A prosecutor is also investigating the matter.