Defense lawyers cross-examined the prosecution's star witness on day 35 of the Jodi Arias death penalty sentencing retrial on Thursday.

While being cross-examined by attorney Kirk Nurmi, Dr. Janine DeMarte admitted that Arias, who has been convicted in the murder of her ex-lover Travis Alexander, suffers from a mental illness. As a result, several court watchers agreed that this will help the defense prove their case that Arias should not be put to death.

"It's good for the defense because maybe they can get one person on the jury that thinks 'I don't know if I can give somebody with mental illness the death penalty.' So that puts something in the jurors minds to think about," said court watcher Jen Wood to KHPO.

Dr. DeMarte's statements on Thursday also contradicted the testimony that she gave earlier in the week when she refuted claims that Arias was a victim.

While on the witness stand on Wednesday, the psychologist described Arias as an extremely jealous stalker with borderline personality disorder and a fixation on Alexander, reports Fox 10 Phoenix. She also said that Arias refused to let him move on and resorted to spying on him and confronting other girls that he dated. She went on to say that Arias was prone to manic episodes of extreme happiness and despair and discredited defense arguments that Arias murdered Alexander as a result of abuse she endured by him and her own family in the past. 

On the day prior, prosecutors presented the jury with sexually explicit text messages that Arias exchanged with Alexander to show that she was enthusiastic about their sex life and cast the convicted killer in a negative light.

Although Arias was found guilty of first-degree murder last May in the death of her ex-boyfriend, in her first trial, jurors failed to reach a unanimous decision on her sentencing. As a result, the retrial will determine whether she should be sentenced to death, life in prison or life with a chance of release after serving 25 years.

According to medical examiners, Arias stabbed Alexander 27 times, primarily in the back, torso and heart in his Phoenix home. She also slit Alexander's throat from ear to ear, nearly decapitating him, and she shot him in the face before she dragged his bloodied corpse to the shower and took pictures of him.