This meant their money no longer could be exchanged for gold.

这意味着他们的钱不能再兑换成黄金。

That lasted until 1971 when President Nixon announced the U.S. would no longer exchange dollars for gold at a set price.

这种情况一直持续到 1971 年尼克松总统宣布美国不再以固定价格将美元兑换成黄金。

The time since that was around the same time of a long exchange of messages and phone call with a certain person helped the investigators investigate specifically on someone else asked the right questions and close the case.

这之后大约是在与某个人长时间交换信息和打电话的同时，帮助调查人员专门调查其他人提出的正确问题并结案。