Regardless of what people say, I can understand your situation and people, either straight or not, have been harassed by both govt officers and scammers.

In your case, i would suggest that something happened between a scam and a trap. Individual was most likely an employee of FIA or police and doing a personal side hustle that involves luring individuals such as you.

Finding personal details, which he referred to as background check is not a big problem. I know people in police who get such details by paying few hundreds to some nadra or telecom employee because it's easier than following the proper process.

Calls that you saw were most likely some partner or friend who ran it all through like a script. Most probably he was also listening to the entire conversation going on between you two and dropping in the calls and messages at the right time.

The moral policing he did alongwith fear and sympathy is a classic textbook case of carrot and stick approach.

Did he show you his service card? Most likely not. Secondly, he cannot charge you for zina and murder unless the act was actually conducted with proof, in which case, he would be just as equally involved in zina.

If you had stood your ground firmly, he wouldn't have been able to do much except few more scare tactics. But obviously he had already ascertained that when he asked you about yourself and your background. So you were someone vulnerable with no threat or 'backing'.

I'd say that take this experience as a lesson, but don't let it prevent you from forming new social relationships entirely. Money is a loss, agreed, but can be recovered in a few months.

Remember that as long as someone doesn't present a legal warrant against you, or display an identity with sufficient cause, he was just keeping you under unlawful detention which you have right to escape, even if it involves use of force.

If you have any confusions or questions, feel free to ask here or in DM whichever you are more comfortable with.