My friends and I were cheated a lot of money by a friend who has escaped to the United States 2 years ago. And we believe he has overstayed his visa. He is trying to get a green card by marrying a US citizen but the process has not been finalized. I am wondering how we can report this case to the immigration officer in the US in order to get him back to his home country? He is now living in Miami. Since I do not know anything about US immigration law, I would appreciate if anyone can give me advice on this. Thank you very much in advance.