Probably his first capital crime, because while he planned it, he screwed up too much. However, he may have done other serious crimes before this, like stalking, window peeping, flashing, burglary, and rape. But if he's killed before, that's possible too. We can be confident Pennsylvania is looking hard at unsolved cases where this psychopathic preadator lived.
It does seem he's not just guilty but incompetent because he used his own car, left a knife-sheath, was utterly ignorant of home security cameras, had previously stalked the house with his phone's GPS footprints all over the place, and probably had contact with the victims at the Mad Greek restaurant with its partly vegan menu.
The restaurant seems like where he fixed on MM and/or KG. Which one he fixed on or interacted with may not correspond to which one was more brutally attacked. It could have been both. Either one of them could have set him off into some sort of narcissistic rage if he demanded to know if his food was served with brand new pots or<modsnip - off topic>
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