MARTINEZ, Calif. — Eli Polk completed an eighth and final contentious day on the witness stand Wednesday, telling jurors that his father's stabbing death could have been prevented if someone had spoken up about his father's abusive behavior toward his mother, murder defendant Susan Polk.

"Isn't it true that your dad did try to prevent it, and now he's dead?" the prosecutor asked, referring to phone calls the victim made to police in the days before his wife stabbed him to death with a paring knife in their $1.85 million home.

"First of all, I believe he attacked her that night and she defended herself," Eli said, adding that his father had "every opportunity" to try to make his marriage work.

"Your father's dead, isn't he?" the prosecutor asked.

"I'm not answering that question," Eli said.

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California housewife Susan Polk, 48, is defending herself at trial against the October 2002 first-degree murder of her 70-year-old psychologist husband, Dr. Felix Polk.

Shortly before the incident, Polk had learned from her divorce attorney that she was about to lose the couple's home, custody of their youngest son, Gabriel, and a significant portion of her spousal support.

Prosecutors say she then decided to kill her husband of 20 years.

But Polk claims she acted in self-defense against a Svengali-like husband, who first became her lover when she was his 15 and his patient.

Eli, 20, is her sole defender among her three children. Gabriel, 19, and Adam, 23, have testified for the prosecution that their mother is delusional and openly fantasized about killing their father.

Eli told jurors that his father was mentally and physically abusive and that Felix wielded his power over the courts and as a secret Israeli intelligence agent to oppress his wife and continue his violence upon the family.

No evidence has been presented to support Eli and his mother's claim that Felix Polk was a Mossad agent.

Eli also said that his brothers' testimony was influenced by attorneys and other individuals who have conspired to "loot" the family's estate.

"So, does crime pay?" Polk asked her son Wednesday.

"Well, I understand Adam and Gabriel didn't bother getting up here to tell the truth," Eli said.

Spending spree

Eli's testimony, while heartfelt, was marred by his personal troubles over the years, and by his and his mother's unruly behavior in the courtroom.

Polk objected no less than 50 times during roughly an hour of Eli's cross-examination Wednesday, arguing with the judge and the attorney, and interrupting so frequently that the court reporter — who cannot type while more than one person is talking — threw up her hands and said, "I can't do this. I'm just going to go."

"OK," Polk said, smiling. She has previously accused the court reporter of making faces at her and purposely leaving things out of the record.

During his cross-examination, Assistant District Attorney Paul Sequeira pointed out, through Polk's own e-mails to her son in summer 2003, that Eli had his own issues with money.

"Stop spending!" Polk had written her son in all capital letters. "No impulse shopping!"

Eli admitted he spent nearly $40,000 worth of his inheritance in just three months, while he was living in a fraternity house at his brother Adam's UCLA campus. He said he paid attorney fees, bought clothes, and ate his meals out because the fraternity had no refrigerator.

Sequeira also drew on Eli's extensive criminal record, including separate incidents as a juvenile involving possession of marijuana, harassment of another student, and battery, as well as his adult cases including a 2005 felony conviction for evading arrest and a recent domestic violence charge for which he is currently awaiting trial.

Eli and his mother are both in custody and claim they have been the victims of malicious prosecution. Eli testified that his father, who once served as chief psychologist of Alameda County conspired with judges to mete out harsh punishments on him as a juvenile.