By this point, the case of Sen. Bob Menendez (D-NJ) is a sprawling and murky one. The FBI and a good deal of reporters have been looking into Salomon Melgen, the doctor, businessman and political donor who is closely connected to the senator. But back before things got to this level, there was a tipster who went by the name Peter Williams pointing the FBI and others in Menendez and Melgen’s direction. Now, Williams is nowhere to be found, and some are questioning the credibility of his claims. TPM’s Eric Lach looks into the history of the this mysterious tipster.