The best predictor of BPD is daddy running away or dying at a young age. But for fear of feminists, a mainstream article is not allowed to say that.
The very first criteria the article lists, 1) Frantic efforts to avoid real or imagined abandonment, is completely wrong as well. BPDs do the opposite; they create situations where abandonment is certain to occur. They can't live without abandonment. Killing the guy is actually a cementing of the abandonment feelings. Now she will always feel them.
I have a bpd ex who was involved in a murder, but it was a current boyfriend who killed an ex who had gotten drunk and decided - at the urging of a second ex - to go to their house at 2 am and talk her into going back to him. The guy who got killed was little, about 135 pounds, and the guy who urged him into going was a big guy, 300 pounds, and said he would protect him. Instead, he ran away immediately. Her live-in boyfriend beat him unconscious, then kicked him in the head until his neck broke. There were no witnesses, so he only got 8 years and served 3. They got back together after he got out, then he beat her up and went right back to jail.
I can't see my ex ever killing anybody herself. She would just manipulate a man into doing it for her.
I would lean more towards Arias being bipolar rather than borderline. It is likely she would get a professional diagnosis for both. But I think the bipolar disorder would be responsible for more of her behavior than BPD.