I have a detailed book on my shelf, published recently, where sworn US officials, took money and forged documents, then lied in court, multiple times, and it took years, many years, to get the evidence. Some attorneys involved were so mad about being lied to, with an unsupportive Federal Judge doing nothing, that parts of the case went to the US Supreme Court to challenge the authority itself. Read that book and get back to me.. 2010s era

edit the point here is - getting a "trusted party" is in fact, not easy, and certainly not "a bank" as a universal answer.. find your own copy of this book, it is repeated a hundred times, every decade.