PHOENIX (AP) -- Jodi Arias' defense attorney worked Wednesday to undo any damage to the credibility of an expert witness who diagnosed the defendant with post-traumatic stress disorder and amnesia after a withering cross-examination that called into question his techniques and testing procedures.
Psychologist Richard Samuels resumed testimony for a fourth day Wednesday 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.
Prosecutor Juan Martinez previously seized on multiple lies Arias told Samuels throughout the process of his evaluation, at one point getting the psychologist to acknowledge that he should have re-administered at least one test he used to come to his PTSD diagnosis. Martinez questioned how Samuels could have come to any definitive conclusion for a diagnosis based upon Arias' lies.
Samuels insisted his diagnosis was accurate.
"The process of forming a diagnosis is not a simple process," Samuels testified Wednesday. "The fact is that it's necessary to obtain information from as many different sources as you can."
Arias faces a possible death sentence 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.
Defense attorney Jennifer Willmott spent much of Wednesday questioning Samuels about his testing procedures. When Samuels initially began his evaluation of Arias, she was sticking to the intruder story.
Willmott went over each question and Arias' answers with Samuels.
"Did she think her life was in danger?" Willmott read.
"Yes," Samuels replied, reading Arias' answer.
"Did she feel helpless?" Willmott asked.
"Yes," Samuels said, explaining later that his diagnosis would have remained unchanged whether Arias was responding to the questions still telling the intruder story or claiming self-defense.
"If the answers remained yes before and yes after, would it have changed the score at all?" Willmott asked.
"No," Samuels said.
He said Arias also answered "no" to a question about whether she was having nightmares.
"This is a score where you could exaggerate if your intent was to skew the score in your favor," Samuels said.
He said the PTSD test was merely one tool used to come to his diagnosis.
"I based the information primarily on my interviews, the crime scene photographs and descriptions, interviews with family members, police reports, emails, text messages and the psychological tests," Samuels said.
Martinez had also questioned Samuels' credibility, accusing him of blurring the line between objective observer and therapist when he bought Arias a self-help book about building self-esteem.
Samuels denied the accusation.
"Is there ever blurring of the lines between evaluator and therapist?" Willmott asked.
"There should not be," Samuels replied, explaining that sending Arias the book is not considered therapy.
Later Wednesday, the judge was set to pose juror questions to Samuels, something allowed in Arizona criminal trials.
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 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 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 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. She has acknowledged lying repeatedly but insists she is telling the truth now.
© 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.