The ABA Journal has an article on the legal issues relating to the crash of the Columbia.
First, there is a doctrine in U.S. law of posse comitatus (‘to be able to be an attendant’ according to Gifis’ Law Dictionary, aka Barron’s Law Dictionary – the mass market edition is cheaper and the content identical), which (says the ABA Journal) forbids the military from enforcing civilian law, so no soldiers around when people were arrested for stealing debris.
Then, had the material been hazardous, jurisdiction problems would have been considerable.
Finally, there is the question of damages for the next of kin. Their chances are slight, as it appears government immunity will apply. Government immunity (or sovereign immunity) has a long tradition, taken over from the English rule, ‘The King can do no wrong’, and applied to the president and government of the USA.