Much recent work has focused on the process of auditing the results of elections. Little work has focused on auditing the e-voting systems currently in use. The facilities for doing the former include the voter-verified paper audit trail; unfortunately, that VVPAT is not particularly helpful in tracking down the source of errors within e-voting systems. This paper discusses the need for a detailed forensic audit trail (FAT) to enable auditors to analyze the actions of e-voting systems, in order to demonstrate either the absence of problems or to find the causes of problems. We also discuss methods to prevent the use of the FAT as a covert channel for violating the necessary properties of secrecy of the ballot, so voters cannot sell their votes, and anonymity of the ballot, so a third party cannot associate a particular ballot with the voter who cast it.