I am so sorry to hear about this... he is very beautiful and looks much like my roo Baby that I had when I was 6
Without going too much into unpleasant detail, I have heard of / experienced problems with two things that I know will do this - raccoons and possums. I cannot have respect for something,
anything, that kills for sport and doesn't even have the deceny to eat what it has taken. I went the next day (thankfully I did not lose anyone to these scummy jerks, friends have, as I caught them trying to get into my coop at dusk and chased them off with a bat) and bought a trap for them. They don't seem smart enough to be suspicious of it, and the first was caught less than 12 hours after I set the trap. I baited with an old, unthawed beef bone, not even meat, tied with a piece of string to the back of the trap so it could not be made off with.
I hear people say to relocate them, the idea of which I was never fond of... I tried it once with a lot of persuassion from my friend (who knows why) and the bloody thing came back within a week... we took it about 10 miles from our place and it found its way back. How do I know it was the same one? It was missing an eye, lol. So I just get rid of the darn things now. I don't seek to harm, or inflict damage without cause, but when anything threatens my family or friends -which very much includes my pets - that threat has the *pleasure* of getting neutralized.
I am not sure what size your property is, what it is like and all, but is there is an area you have reason to be suspicious of, like somewhere these critters might hang out in til dusk, I would advise trying traps of the appropriate sizes. Try placing them near their hideouts, and in the direction / path they would take on their way to your pets. I have had much success with this tactic.
Again, I am so very sorry to hear about this, and all stories like this... it breaks my heart because I have also had to deal with losing dear pets that meant so much to me overs the years, they are like my children and I can totally sympathize. I wish you and yours the best, and especially your little Abraham... give him a hug for me.