But without key evidence, pursuing a conviction is nearly impossible. For investigators, the story is often the same: they know a murder took place, they may even know who did it. A devious killer who hid his wife's body under a thick cement patio. A hiker brutally murdered, then thrown off a cliff in a remote mountain range.
A body stuffed in a car trunk swallowed by the swirling, muddy waters of the Missouri River.
