"They don't have the control they would like, so they create their own game," she said. "Every psychopath is mostly about power and control. If you're useful, they'll use you and manipulate you. And if you're in the way, they may eliminate you."
This was the case with Jason Wilkman, a 6-year-old boy who inadvertently crossed Shiue's path and whom Shiue murdered.
"The little boy simply got in his way," said Brown. "A psychopath has no empathy for anybody else, so it's collateral damage."
Experts said Shiue lacked normal moral restraints. He felt no remorse, which made it possible to act upon his fantasies. Psychopaths are "not concerned about the other person's feelings or the well-being of the person," Brown said. "They have no empathy. So the other person is merely a pawn to them."
They "manipulate everything they can in order to get what they want," she said.
According to Brown, abducting Stauffer's daughter was no accident. With the child in tow, Shiue expected Mary Stauffer to be more compliant. "You take the child so that you can have control over the female, because she will do a lot more if she's afraid for her child's life."
It was a need for control and power, not a desire for sex, that motivated Shiue's behavior while he held Mary and Beth Stauffer captive.
He raped Mary Stauffer daily, not because of an interest in sex but rather because he wanted to humiliate her and exercise his power over her, Brown said.
He "has partial insight from time to time that what he's doing is wrong," said Reitman. "He wants to rationalize and convince himself that she loves him."
Shiue manipulated Stauffer into saying, "I love you," pressuring her to be more affectionate to ease his own guilt.
He even went so far as to place a plastic bag over Beth's head, only removing it after her mother kissed him on the lips.
"He wanted to watch [Stauffer] squirm. He wanted to watch her struggle. And he just kept playing with her," said Brown.
A complicated split ruled Shiue's mind: He was both a sadist and delusional, experts said.
"He bounces back and forth through his being sadistic, wanting to punish her, 'She harmed me' to 'I love her,'" said Reitman. "He can have those moments where he wants to inflict humiliation and pain, because that's an arousal for him, but in his mind, he also loved her."
When Shiue encountered Stauffer in court, he attacked her on two separate occasions, releasing his "homicidal rage" and revealing that that he was deluded, said Reitman. "He really thought at times that she was his lover. He wanted that. That was his wishful thinking."
"He fixated on [her] for 15 years. He kidnapped her, raped her, threatened to kill her daughter," said Reitman. "He killed a 6-year-old boy. He butchered her on the stand because she lied -- in his mind. He might feel that he spent 30 years in prison because she lied. We don't know."