"Do I think he has given money away? Yes."

The bizarre case began when Donaldson, referring to himself as an international investor named "Charlie", set up a meeting with the bank's manager, according to the FBI in documents filed in Wyoming's US District Court.

During the meeting, Charlie said he owned a business in Mexico, was robbed and then four men who were Vietnam veterans and involved with a drug cartel approached him with an offer to help find the people responsible for the theft.

The bank manager said Charlie then recounted a story about how the Vietnam vets took Charlie up in a helicopter with two unknown males, asked one of the males about the theft and, when he refused to answer, tied a rope around the man, lowered him out the helicopter and "dragged him until the only thing left was a bloody rope".

The bank manager told authorities that when he reached for an alarm button under his desk, Charlie warned members of the drug cartel had given him a note which said "four military grade explosives" were placed outside the bank and if he did not comply with their demands there "will be blood and carnage" and the manager would be "hunted down and killed".