It is appalling how one "human being" can prey on the grief of another in this way.
This is nonsense designed to get you to pay more money.
What possible offence could you have committed ? and what would it have to do with the FBI which is an American organisation?
Please ignore these messages and I sincerely ***** ***** meet someone who will not abuse your kindness and trust in the future.
Why would the bank give the FBI your details ? what offence have you committed?, what has it got to do with the FBI? it is all a complete nonsense.
Please ignore these messages, he will ask money from you to help you sort this out next.
The only thing you can do at this point is ignore all contact from them, there's no way they can charge you for "fraud", if it's YOU who's been defrauded.
Please, don't answer the phone to them or respond to any emails
This is a classic and very hurtful scam, don't make it any worse by responding to it, or getting upset by it.
You just have to live and learn from the mistake, there are evil people out there, unfortunately. :(