Shrimp trauma: do I have a predator?

Last week in a quick scan of my 20L I would count ~ 20 neocardina from half inch up to adult. A few days ago I noticed these. They did not appear to have been fed on, just torn apart. Tankmates are Neon Tetras and Julii Cory's, none of which seem to ever notice the shrimp. A count last night came to 5 adult and 7 juvenile, plus several hatchlings. Should I hunt a larvae, or may there be another issue I don't know about?