What trails does a missing person leave behind?
jacquesm: With a cell phone you can track someone within a few hundred meters in a city cell, in a rural cell within a kilometer or two.As for 'trails', try the past, if the person used a computer and you have access to it (legally) you could try to figure out what they were doing before they went off.Browser histories, email, IM & skype, msn and IRC chat records as well as the contents of input fields on forms can be quite revealing.