There is an inherent tendency to suppose guilt, when someone lies about an incident. Many applauded when Martha Stewart was sent to prison for 5 months for lying to investigators about some stock dealings. The charge was not perjury, rather, "obstruction of justice" If someone lies about, say, a relative's whereabouts, though the lie may have been told to protect someone's privacy rather than obstruct justice, it is a presumption of guilt on the part of the person "hiding" information, as well as the object of the investigation.
