Greece ? Police in Greece have arrested four suspects who stole $4 million in the country’s biggest-ever bank heist, local media said Wednesday.

On Friday, four armed men held up a bank in Thessalonki, in northern Greece, fired warning shots into the air, tied up the guards and escaped with the money.

Later, one of them, a police officer, surprised investigators by returning to the bank for a bag of money dropped during the raid. He was promptly arrested and later revealed the names of his three accomplices, including a 45-year-old bank employee.