>>535629418
Assuming the game wants actual hooks as opposed to just hook states from the counter in the Killer's HUD, then yes you are good to kill them any way you want after you've collectively hooked them all 9 times.
"By your own hand" includes the free mori on the last living survivor, moris from offerings, and "mini moris" that some Killer powers give. If you're trying to maximize that particular category, you only really need to be careful with Sadako and Pig; they're the only two (I can think of) that let you kill a survivor without having to hook them twice first.