Police investigation on receipt of written complaint

If the police officer investigating the case had come across the ingredients of a cognisable case against you he would definitely have ensured filing of an FIR against you. This is what a landmark Supreme Court judgement by a constitutional bench (Lalita Kumari case) on the issue prescribes. In the said case it seems that they may not be lodging an FIR against you.

You can file a case for malicious prosecution only when you are acquitted in a case after undergoing a prosecution. Here in this matter, no case has been filed against you even.

Receiving a complaint against you and conducting some sort investigation on the matter are legally permissible duties that a police officer is expected to do as per our criminal prosecution practices.

Try to find out status of the complaint, if the police officer is not telling you personally, use Right to Information for knowing status.