I'm pretty sure deaths will parallel character, but the skrull might not be killing people via their characters route and they presumably whacked fist, as for 'torn in half' I'd say that's more likely a super-strength thing, grab head, grab foot, yank, or grab each shoulder and pull since it didn't say which halves Skrulls on the whole aren't known for their super-strength though in a comic book context that doesn't mean much beyond "Can't bench press a car", and they don't gain someone's powers when shape-shifted to them, of course it could also have been done without sheer muscle - telekinesis, cybernetics, a weapon that leaves similar effects, etc. such that pretty much everyone has at least one of their 4 characters who could have done the deed, and again our enemies are shapeshifters so character analysis to cause of death isn't likely to get us much progress at the moment I'm afraid.

The next point I want to raise, a #3 if you would, is why Fistofpainx? None of his character claims scream "Threat" and he was a mason, so I think maybe that ally or allies should come forward, the infiltrated mason circle has been done a lot but it can still work. So points of note, Scarlet Witch is the twin sister of Quicksilver and daughter of Magneto, both of which are on the character claim list, and a member of the avengers, who many of us listed members of in our 4 claims. I think we need to hear from those allies, preferably voluntarily, but just as encouragement, let me point out that it won't be too hard to figure out who that person(s) are, so stepping forward voluntarily would probably behoove you.