There is no way the police can help in this because this guy can tell more lies and convince them that actually you are at fault. These one-to-one dealings have to be done carefully. No advance should be paid to anyone for any dealing unless you know him very well or there is a written transaction. I sympathize with you. It is not only you, lot of people get duped everyday in this manner. So you can only consider this as a lesson and be more careful in future.