Lots of pieces of clothing,
shoes & towels have been
found by divers.
Sharks can and do chew a
body into pieces. One shark
grabs it, his mates soon join
in soon as they smell the blood
in the water. No more body.
They don't get every single piece, is what I'm saying. There would be some evidence, parts of a hand or foot or skull or bits of clothing they should be able to identify.