Bro: Murderer.
Prison Guard: Murderer.
Tenma: Paraphilia. Aka mentally screwed up.
Rukia: Also screwed up. Certainly doesn't act like a victim. Best read is that she does enjoy seducing people and having them act on her behalf. She knew her brother killed her first husband, but not only does not stop him, but also goes out and gets another husband for him to murder. Plus earlier, she knowingly participated in brother scheme to blackmail her adult lovers while she was in high school.
So, even if she never gave a command to the two who killed for her, she still knew what they were doing, and set things up so that they would do so. So she is at least a participant, and depending on how you look at it, the instigator.
