My Halloween hisser mysteriously died!

[JadeBlue]

Hello! I have 2 hissers right now, a Halloween and a Madagascar. I acquired the Halloween about 4 months before the other. Tonight, I went to mist their enclosure and replenish their water, and the Halloween hisser looks dead. His cerci looks chewed or broken off, and I don't see it anywhere in the enclosure. He shows no signs of life. The Madagascar is just chilling under some bark, doing just fine. I'm quite distressed by this. Any ideas what happened?

 

[Hisserdude]

Were they adults when you got them? It's possible it was just an old adult when you got it, and it died of old age.