Visa refused by consular after being in AP for 18months.

[bdtiger 0]

Hi, I had my interview on the 3rd of April 2017 and the consular officer kept all of our documents and evidence and told me that they will contact me once the AP is completed. I waited more than a year and then they sent me another mail on the May 2018 saying I have to give another interview. This time the interview lasted for over 30minutes and asked me everything in brief. This time I submitted many other documents too which were recent as in pictures and chat and call logs. Again the consular said he will let me know and later that week an investigation team showed up in my residential address and verified everything and told me soon I will be hearing from them. After 4 months I receive a letter saying that my visa was refused and they are sending the case back to the USCIS. They didn't mention much in that email and told me I can make a direct contact to USCIS once they receive the packet. Can anyone help me with this or advice us with a neccessary step to take?

Thank you,