PHOENIX -- Jurors in Jodi Arias' murder trial paid close attention to an expert witness's testimony that he diagnosed her with post-traumatic stress disorder and amnesia as many of the questions from the panel Thursday focused on specific details of his evaluation and how he could come to any conclusions relying on Arias' repeated lies.

Psychologist Richard Samuels, a defense witness, testified for a fifth day Thursday after telling jurors he diagnosed Arias with PTSD and dissociative amnesia, which explains why she can't remember much from the day she killed her lover. Samuels said he met with Arias a dozen times for more than 30 hours over three years while she was jailed.

Arizona is one of a few states where jurors have a right under state law to query witnesses through written questions posed by the judge. In most other states, it's up to the judge to determine whether to allow it.

By midday, Samuels had answered more than 70 questions, with more to come.

"How can we be certain that your assessment of Ms. Arias is not based on her lies?" one juror question read.

"The diagnosis of PTSD is a function of an evaluation based upon my 35 years of experience in working with individuals with PTSD," Samuels replied, noting he can say with "all reasonable psychological probability" that she meets the criteria.


Advertisement

Arias faces a possible death sentence if convicted of first-degree murder in the June 2008 killing of Travis Alexander in his suburban Phoenix home. Authorities say she planned the attack on her lover 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.

When Samuels initially began his evaluation of Arias, she was sticking to the intruder story, and prosecutor Juan Martinez repeatedly questioned him on how he could have concluded anything with certainty if Arias was still lying. Samuels insisted his diagnosis was accurate.

Jurors asked if Samuels could be certain that Arias wasn't still lying about the day of the killing.

"Not with 100 percent certainty," he said. "Psychology is the science of behavior so we're seldom 100 percent sure."

Samuels testified previously that Arias was likely suffering from acute stress at the time of the killing, sending her body into a "fight or flight" mode to defend herself, which caused her brain to stop retaining memory.

The jury asked Thursday whether this scenario could occur even if this was a premeditated murder, as the prosecution contends.

"Is it possible? Yes. Is it probable? No," Samuels said.

"Can acute stress occur if someone plans to kill versus defending themselves from danger?" the panel prodded with another question.

"Um, homicide is of a different nature," Samuels said before being cut off by an objection from the prosecutor.

"Possible but not probable," he continued.

The jury later asked if it is possible for a defendant to trick a psychologist into thinking they have PTSD.

Samuels again said it was possible but unlikely, noting when a person is telling the truth their stories tend to change slightly, with increasing or decreasing detail, as they are questioned repeatedly. He noted how Arias' intruder story remained exactly the same during repeated questioning until she eventually told him it was self-defense.

"It is my feeling that once the story changed (from intruders) she was essentially telling actually what happened," he said.

Once juror questions conclude, attorneys on both sides will have the opportunity to question Samuels again based on his answers.

Alexander suffered nearly 30 knife wounds, was shot in the head and had his throat slit before Arias dragged his body into his shower.

Arias spent 18 days on the witness stand. She described an 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 said she recalls Alexander attacking her in a fury. Arias 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 working on an alibi in an attempt to avoid suspicion. She said she was too scared and ashamed to tell the truth.

None of Arias' allegations of Alexander's violence, that he owned a gun and had sexual desires for boys has been corroborated by witnesses or evidence.