@CNN: A starting point for investigators trying to trace the bombs sent to Democratic figures and CNN this week: the postmark. But in some cases, it appears to be a missing clue. https://t.co/G7xq0jfuSC

@CNN: A starting point for investigators trying to trace the bombs sent to Democratic figures and CNN this week: the postmark. But in some cases, it appears to be a missing clue. https://t.co/G7xq0jfuSC