In Laura's eyes, Libby was the black sheep of the family. She did drugs, she left home, had premarital sex, and the worst sin in her eyes, she had an abortion. When Libby was at her lowest point (committing suicide), Laura saw this as her opportunity. She manipulated her sister into luring out Cassie and Vlad to avenge her death. Libby would do this by using the Mosaic Man, to draw them out and then finish them off. During this Libby would use a spell book, to cast luck on a number of Sante Muerte figurines to atone for her sins.
Eventually with Vlad by her side, allowed herself to become possessed by Laura by submerging herself in a bathtub full of water. Vlad learned that after Laura's disappearance (as her family was unaware she had died), Liberty attempted to commit suicide. From death's realm, Laura kept Libby's soul from leaving her body and once Liberty recovered, Laura led her sister to find necromantic spells so that the two sisters could communicate. Laura also taught Libby how to look for other necromancy tomes.
After learning from Vlad how Libby tried to use necromancy to bless others with luck, Laura denounces her sister for making a mockery of her own goal to destroy Cassie and Vlad. Laura tries to coax Vlad into killing her again which would effectively kill her sister, Liberty. Vlad simply tells Laura to "shut up" and lifts Liberty's body out of the water, breaking Laura's possession over her sister. Libby's not seen afterwards.
But a future version of herself is seen in the Hack/Slash annual 2010: Murder Messiah. She was something of witch vigilante, trying to protect innocent. In the future, the Black Lamp Society released a toxin that turned a large number of people into killers. At some point, she met Vlad again (who had been imprisoned) who told her of Samhain and of Sixx's powerful guitar. She and Pooch would go after the guitar to travel to the past and stop the horrible future. But Samhain or Akakios caught up with them and attempted to stop them. Pooch was killed in the struggle.
Not having a lot of time, Libby used a spell to kill some of his men and then used the guitar to take her to the past. While she had come to Chris and Lisa's town, she wasn't in the right company. She found herself in front of Sheriff Maggie Reilly, not knowing she was one of the Society's agents.
She, desperately, tries to warn her of Samhain. That the Black Lamp Society would release a toxin and if they did so many would die. Maggie, coldly, shot Libby in the face to prevent the truth from coming out. But her murder would haunt her.