Why are my hermits dying... or rather... being killed?!

I just got home from work and noticed yet another lifeless set of scarlet hermit crab legs lying on a rock far from any shell. It was missing its eyes and it's backside, which I'd assume is the meaty section of the crab as it would be on a lobster. This is the third victim I've had in about a week! This is really starting to aggravate me.

Victim #1 - I bought 3 scarlets and three snails to put in my tank about two weeks ago and a few days later I noticed a lifeless pair of legs attached to the head of the animal with no backside and no shell anywhere nearby.

Victim #2 - Noticed the lifeless body a few days later. This could potentially be the same as I didn't remove the 1st dead crab.

Victim #3 - I explained above. However, I suppose this could be victim #1 as well, but doesn't sound likely as the body was on top of one of my pieces of LR.

In any case, whether it be one death or three, I'd like to try to figure out what's going on. I've still got a feeling it could be a mantis, but if it is I haven't seen it and it's been about 5 weeks.

I really do not have that many potential predators in the tank... at least I don't think so. I know sometimes other hermits will kill each other to take shells. I have some hairy white looking crabs that I think might be potential bad guys as some of them are getting large in size (relatively speaking). Then there's also the possibility of the mantis. The other thing that's puzzling to me is that I can't find any empty hermit shells anywhere.

If anybody has any thoughts, I'd love to hear them. I'd really like to not have to replace my entire scarlet hermit group, which should've been up to ~11. All the snails I've added appear to still be alive.

I'm thinking of the potential of molting as well. I'm just trying to figure out how intact the molted shell should be if that is the case...It looks like the claws and legs are completely intact.

Sounds good. Just to be sure though I'm going to start keeping an eye on how many are alive and moving in the tank so I can keep tabs.

So here's a new theory. Could it be that the hairy crabs in the tank are what's going after everything? I've been going back and forth about what's been going on in the tank. I've come to the conclusion that the "victims" I described above were merely molts, however I've been also starting to notice scarlet legs and even porcelain crab claw arms (only the arms) laying around on the sand.

I don't think my pistol shrimp, wherever it is, is the cause of this and I'm borderline about a possible mantis. I kind of doubt it's a mantis since I haven't seen one in the entire time I've had the tank running (approx. 6 weeks now) and I keep a close eye on what's happening in there.

I've been pulling out several nickel-sized hairy crabs lately. In fact just last night within an hour or so my friend pulled out two good sized ones alone. I'm trying to snag them when I see them. Could these guys be the culprits after all? I really don't want to lose my whole cleanup crew due to these things and I definitely don't want to lose my two peppermint shrimp... not to mention my new mushrooms and all the corals that came on my rocks to begin with.

Are these guys really that dangerous?

p.s. Most of the ones we've pulled out either have a black or dark brown tip on the ends of their claws.