The Jodi Arias sentencing retrial continued on Wednesday as a key witness on the defense team returned to the courtroom and testified that Arias was mentally ill when she brutally murdered her ex-boyfriend Travis Alexander in 2008.

Earlier in the retrial, psychologist defense expert Dr. Robert Geffner told jurors that the convicted killer suffered from mental illness, PTSD and abuse by Alexander. On Wednesday, he talked about Alexander's double life as a conservative Mormon and sex fanatic, reports Fox 10 Phoenix. Dr. Geffner will be cross-examined by the prosecution on Thursday.

Last week, the prosecution in the high profile death penalty retrial rested, signaling that an end to the high profile trial may soon be near.

Maricopa County Superior Court Judge Sherry Stephens told jurors on Feb. 12 to expect to continue reporting to the courthouse until the end of February since there could be testimony from rebuttal witnesses as late as Feb. 26, according to The Associated Press.

During the mitigation phase of the trial, the defense team will have another opportunity to persuade the jury not to sentence the convicted killer to death due to different mitigating factors, reports USA Today. 

Following the last witnesses, Arias will be allowed to address the jury directly and offer a plea for her life. Both sides will then end with a closing argument before the jury begins deliberating a life in prison or death sentence.

Although Arias was found guilty of first-degree murder in May 2013 in the death of her ex-boyfriend, 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.