A couple years back, I had some issues with some hybrid mice that were dumped on me. Managed to home most of them, but I kept hold of the best 6 females as they were quite a nice lot & I was planing for a snake then. I decided I'd get a decent male to put with them, but they killed & ate him. Along with another 3-4 after him. Talking to a breeder who'd also had a couple of hybrid (btw, it's feral/wild x domestic mice) litters, I learnt that the hybrid females eating domestic males was a pretty common thing. They were larger than wild mice, but had all the bad temperment. My lot were bred from some 2nd generation hybrids, so they had a few white markings & such, but feral in all regards. I ended up just getting rid of them to the breeder who'd had a couple litters, as she had a few hybrid males who were very skilled at calming their ladies. From what she told me last time we spoke, things were doing very well with the generations after those initial girls.
Admittedly, your girls might just be psychotic ladies, but I'd thought I'd put my peice in