Police are calling to visit thier station in another state

So, I have a friend from a university and I am asking this on his behalf. So he was going through some website and saw one website where he can invest and earn. So he tried investing thousand rupees and was given 300 rupees in profit. He started investing on that company and after sometime he went on to search for a more profit company on a website and started investing on that company which said they would give more profit and it was going great but later he got scammed and lost around 60 thousand rupees. Later on one of the first company he invested on contacted him and inquired on why he wasn't investing anymore and so he told them the truth on how he got scammed by another company of thier such. So as he say out of sympathy they ask him to work for them as their agent. So inorder to get his lost money he did so. Him as the agent of the company was sent some amount of money to his account and was given a bank details of some peoples account where he was to sent that money to and he was given a commission of 2 thousand per day. He said he work their for around 2 months or so and only stop when he received a call from the bank asking him why he has been doing so many transactions from a savings account. So he told the company that he'll not be working anymore but they still send him around 60 thousand but later his account was got blocked and they lost their contact and the money they send him is still on him. Now, the think is he has received a letter from the police station from another state claiming that he should come visit them for some inquiry and have not mentioned anything on the letter. What should he do now?! What would have been the cause of the letter being sent to him?!