Cignarelli did testify as a rebuttal witness in the second trial. Whether the jury found him credible, only they can answer. It probably didn't look good for him that he'd been paid $25k for an interview with "Hard Copy" after the first trial, although he did donate $3k (curiously he insisted it was $5k) to a shelter for "genuinely" abused children.
Some of Lyle's statements were "allegedly", while others are documented. I think Lyle would have been annihilated on cross-examination if he'd taken the stand. A letter he wrote to an ex-girlfriend in which he asked her to invent an incident about Kitty poisoning the food was kept out of the prosecution's case by the judge, who ruled it could only be used to impeach Lyle if he took the stand during the defense case. The Novelli tape that the prosecution wanted to use where Lyle talks about fabricating an Oziel blackmail meeting could also not be used by the prosecution in their case; only to impeach Lyle, and in rebuttal. Lyle would also have been cross-examined extensively about the attempt to bribe his fiancee to say Jose sexually assaulted her, and the letter he wrote to a friend of Erik's in yet another attempt to suborn perjury.
Second-degree murder was an option as well.
Cignarelli's credibility was damaged by his changing of the dates where Erik confessed the murders to him. The version he gave police in 1989 differed from what he claimed under oath at the first trial, hence why he wasn't called to testify in the first phase of the second trial.
The Jamie Pisarcik story (where Lyle asked her to claim that Jose had assaulted her) was brought up in the first trial, by the defense, and Lyle did admit to doing this. So Conn's argument (at least the one he gave
American Justice) is invalid because Lyle's jury from the first trial did hear about it. The "friend" that he wrote to, asking him to testify that Lyle tried to buy a gun from him, Lyle did not go through with it. As for the Norma Novelli stuff, she's not particularly credible either, she couldn't wait to sell that "book" after Lyle dropped her (it's obvious that she was infatuated with him and published the book out of revenge), there's still a question whether Lyle consented to her recording the conversations or not. What I find hilarious is that she claims to have been manipulated by Lyle, when she stated that she never believed that Lyle and Erik were abused from the start, and you'll notice that Lyle does almost all of the talking. Who manipulated who? She has the nerve to refer to him as evil, yet she had no problem visiting him in the L.A. County Jail and performing tasks for him.
Regarding Oziel, don't you find it telling that he wasn't even called to testify? He was found to be so evasive and so untrustworthy that he never even appeared in the second trial. Don't forget that Judalon Smith recanted her confession to police and appeared as a defense witness in the first trial, or that Oziel ultimately surrendered his license after being accused of violating the doctor/patient privilege and having sex with his female patients.
Second-degree murder might have been an option open for the jury in Jose's death, but not Kitty's. Denying the defense the right to call witnesses to corroborate the abuse issues and the family history is why the brothers can now appeal for a new trial.
It's also very telling that the prosecution called a different expert witness to talk about the crime scene and how it appeared the murders had happened, because the coroner who had performed the autopsies on Jose and Kitty, Dr. Irwin Golden, was unable to determine how many shots were fired and the sequence in which they were fired; he was also heavily criticized for the errors he made in the autopsies of Nicole Brown Simpson and Ron Goldman. Instead, Conn used Roger McCarthy of Failure Analysis Associates, who admitted under cross-examination that he had never visited a crime scene, never witnessed an autopsy, nor had he ever seen the impact of a gunshot wound on a human body. So, his computer "re-construction" of how the shots were fired, etc., is questionable at best. The defense called Ron Linhart, the assistant director of the Los Angeles Sheriff's Department's crime lab, who testified that his blood-splatter analysis which contradicted McCarthy's version, and that his analysis showed that Jose and Kitty were both standing at some point when the shots were fired.
The prosecution used a lot of tactics (particularly in the cross-examinations of both defendants) that would not fly today. The homosexuality argument that prosecutors used against Erik in both trials, for one. Not only was it homophobic, but it actually was insulting and demeaning as confusion over sexual identity is often a sign of sexual abuse also (in case anyone else in this thread is wondering, this user and I have had debates on youtube over this case). David Conn had his own motive for wanting to convict the brothers; he wanted to be promoted as head District Attorney and believed that convicting the Menendez brothers would accomplish that for him. After the conclusion of the second trial, Conn was angry and humiliated when he was passed over for promotion, and when he was removed as acting head deputy of the major crimes unit.
Pamela Bozanich made comments on the ABC
20/20 special that Jose was abusive to his sons (especially) and his wife. Pretty much every other time she is interviewed she claims that she knows 100% that there was no abuse. Which is it? Given her role in the infamous McMartin Preschool trial, her credibility is questionable at best.