PHOENIX (AP) -- A prosecutor in Jodi Arias' murder trial on Monday vigorously questioned a defense expert's credibility and the psychologist's diagnoses that Arias suffers from post-traumatic stress disorder, accusing the man of losing his objectivity in the case.
The heated exchange between prosecutor Juan Martinez and psychologist Richard Samuels led to repeated objections from defense attorneys.
Samuels has spent two days on the witness stand telling jurors how Arias suffers from amnesia and PTSD, which explains why she can't remember much from the day she says she killed her lover in self-defense.
"Amnesia is not necessarily a fake or made up kind of occurrence," Samuels told jurors Monday. "It is not as if amnesia can only be made up to cover up something."
Samuels said he met with Arias a dozen times for more than 30 hours over three years before eventually diagnosing her with PTSD and amnesia.
He is set to resume his testimony Tuesday.
Arias faces the death penalty if convicted of first-degree murder in the June 2008 death of Travis Alexander in his suburban Phoenix home. Authorities say she planned the attack in a jealous rage. Arias initially told authorities she had nothing to do with it, then blamed it on masked intruders. Two years after her arrest, she said it was self-defense.
Arias spent 18 days on the witness stand during which she described her abusive childhood, cheating boyfriends, dead-end jobs, a shocking sexual relationship with Alexander, and her contention that he had grown physically abusive in the months leading to his death.
She says she recalls little from the day of the attack.
But as Martinez began his bullish cross-examination, Samuels stammered to explain his techniques and relationship with Arias.
Martinez displayed for jurors a written test administered by Samuels to Arias as he worked toward a diagnosis.
Samuels acknowledged that he knew Arias lied when answering some of the questions, such as one where she said she had previously suffered a life-threatening traumatic event at the hands of a stranger.
"Knowing that this was a lie, you used it and then concluded that those scores ... confirm the presence of PTSD even though you just now told us this is a lie?" Martinez snapped.
"Perhaps I should have re-administered that test," Samuels replied.
Martinez also noted how Arias testified that on the day of Alexander's death, before she killed him, the victim had tied her wrists to his bed as they had sex.
He then pointed out how Samuels noted she had both her wrists and ankles tied.
"Well, that's what I had in my notes," Samuels said. "I don't remember what she told me."
Under direct questioning by defense attorneys, Samuels explained how he was once reprimanded in New Jersey in the mid-1990s when he was serving as an objective evaluator in a child custody case. He said he found both parents to be fit, then later began seeing the man, who was dentist, as a patient.
Samuels said the man couldn't afford to pay him, so he traded his services for dental work, only to later find out that is not permitted under New Jersey law.
Martinez seized on the revelation, accusing Samuels of blurring the line between being an objective observer and a therapist offering treatment.
Samuels said that during his time evaluating Arias while she was jailed, he bought her a self-help book about getting over depression.
"That creates an issue of your objectivity in this case doesn't it?" Martinez asked loudly, saying Samuels had then created a doctor-patient relationship.
"I don't think so," Samuels said.
"You can see there is an appearance here that you're trying to help her, right?" Martinez responded.
"From your perspective," Samuels said.
Alexander suffered nearly 30 knife wounds, was shot in the head and had his throat slit before Arias dragged his body into his shower.
She said she recalls Alexander attacking her in a fury and said she ran into his closet to retrieve a gun he kept on a shelf and fired in self-defense but has no memory of stabbing him.
She has acknowledged trying to clean the scene of the killing, dumping the gun in the desert and leaving the victim a voicemail on his cellphone hours later in an attempt to avoid suspicion. She says she was too scared and ashamed to tell the truth.
Samuels attempted to explain the telephone call as part of the acute stress she was suffering.
"By creating an alternative reality, it's as if it didn't happen and it reduces the level of stress," he said.