I think if there is any traction at all for the defense in Tara L., it's as part of a "temporary insanity" defense, to wit: Tara The Seductress, the experienced man-eater, pounces upon Chris Coleman, who's unhappy, lonely, vulnerable, psychologically fragile, and makes him a victim of her aggression toward her old high school friend.
Using Kama Sutra techniques the likes of which near-virgin Chris Coleman had never experienced in his sweet short life, Tara Lintz wound a web of sex and psychological entrapment to force him to murder his family as the only means to achieve her love.
THAT might work on the One Doofus Juror. Margulis will try to find as many jurors as possible who believe that women carry Evil Powers over men between their legs, that a woman could tease, tantalize, and torture a normal moral man into trading his family's lives for her sexual favors. Why, the hussy was even planning to marry him, and Sheri barely cold! She must have had Chris's man jewels in her purse!
For Chris to be found with reduced responsibility for the murders, then someone else has to carry the burden. If they're going for a reduced charge, like second-degree murder (if they can block evidence, it might work), then Tara has to be an "unindicted co-conspirator" who can't be touched by any laws, but who surely bears some of the responsibility for the murders. They can pretty much say anything about her that they want, and if the prosecution tries to limit her contribution and tone her sexuality down, that might leave a "gray area" that the defense will hurry to paint in the most lurid colors possible.
"Sure, he did it--but she made him do it, and therefore he cannot be found guilty of premeditated first-degree murder. He may even be legally innocent due to diminished capacity because she controlled his mind. He was actually suffering from Stockholm Syndrome, identifying with his oppressor--Tara Lintz."
It might work.