Of course, getting a conviction is going to be difficult, because there's no sign of the body. Just the evidence of a violent struggle. Tufts of feathers strewn across the dark brown earth. Fluffy grey wisps caught on the occasional clutch of weedy grass.
I'm pretty sure the victim was a pheasant. The pinfeathers have that distinctive brown and white chevron pattern you only see on the female. But without a body...
Of course it's possible Grendel's dragged the corpse into her Den Of Death under the leylandii hedge, to feast upon her victim, or maybe it was just a fight. A bit of name-calling that got out of hand. Someone says something they can't take back, and the next thing you know they're swinging punches, pulling hair, fur and feathers flying. Only there's no sign of any injury on Grendel. AKA: Little Miss. AKA: Kitty Pookerton. AKA: Stephanie Meerschaum (when she's ordering pizza, or conducting internet fraud). But she does have prior: mousicide, serial shrew killings, baby rabbits, a greenfinch... Why not a pheasant?
Then again, maybe we shouldn't be looking at just the usual suspects. Maybe we should be opening the investigation up to consider other possibilities. Like the black cat who's come calling over the last couple of weeks. Sitting on the picnic table and howling like his (or her) bum's on fire.
Maybe this is the real villain, and the feathers have been planted to set Grendel up? A backyard turf war.
Or maybe it's something far more sinister...