... is usually regarded as an admission of guilt.
The CIA says it wiped two tapes of interrogations of al-Qaeda suspects to protect the identities of its agents. But human rights groups accuse it of destroying evidence of practices that may be tantamount to torture. US President George W Bush has said he has "no recollection" of the existence of video tapes of CIA interrogations and the plan to destroy them. [BBC News December 7th 2007]
Security guru Bruce Schneier comments: "And those tapes must have been really damning. Old interrogation tapes can yield valuable intelligence; you don't ever erase them unless you absolutely have to."
Of course, tape machines do sometimes fail. For example, 18 minutes of Watergate tape were accidentally erased. Don't worry Nixon, the boffins are working to restore the missing sections.
But if you are caught destroying evidence, people usually put the worst possible interpretation on this.
If you know the effect that your actions are likely to have, and you go ahead anyway, this only makes sense if the alternative is far worse. POSIWID thinking therefore acts as an amplifier, accentuating the whisper of suspicion into a bawl of accusation.