There is a difference between a report being reliable and a report being true. Very reliable reports may not be true, and very true reports needn't be reliable. Reliability is a measure of how much trust we—the audience—place in the reporter giving the account;
I think you mean credibility rather than reliability. Reliable reports must be truthful or capable to be relied on even if we ultimately we don't or won't rely on them. On the other hand, credibility indicates how much trust the audience should have in an account. False reports may be credible but by definition, they are not reliable.
There is a good reason why real investigations prefer live testimony of witnesses over affidavits from witnesses. Most of the indicators of credibility (particularly witness demeanor, slip ups during cross examination, eye contact, etc.) are simply absent from written testimony.
quote:To determine the truth of an account we can do only one thing: examine the account against physical evidence and check for corroboration in other accounts.
I think ignoring the credibility of the accounts is a huge mistake. No investigator would do this.