Things heated up in Arizona's Maricopa County Superior Courtroom on Monday during a fiery exchange between the state prosecutor and a star witness on the defense in the Jodi Arias death penalty retrial.

Back in May 2013, Arias was convicted of brutally murdering her ex-boyfriend, Travis Alexander, 30, inside of his Phoenix home in June 2008. According to medical examiners, the 34-year-old boyfriend killer stabbed him 27 times, primarily in the back, torso and heart. She also slit his throat from ear to ear, nearly decapitating him, and shot him in the face. Although she was found guilty of first-degree murder, the jury failed to reach a unanimous decision on her sentencing. As a result, the jury in her current retrial will determine whether she should be sentenced to death, life in prison or life with a chance of release after serving 25 years.

On Monday, Dr. Miccio Fonseca, a clinical psychologist who specializes in twisted sexual behavior, returned to the witness stand to be cross-examined by prosecutor Juan Martinez. For the past two weeks, the relationship expert has testified on behalf of the defense about Alexander's inner conflict between his religious conviction and sexual desires.

She stated that Alexander had a mastery of deception and a "Dr. Jekyll and Mr. Hyde" personality. She also alluded that he communicated having sexual desires about minors, reports ABC 15 Arizona. As a result, her testimony served to build the defense's argument that Alexander was a sexual deviant who emotionally abused Arias.

During a very contentious cross-examination, Martinez repeatedly attacked the doctor's credibility, objectivity and memory. In turn, Fonseca turned to the jury and accused Martinez of traveling down a "slime highway," reports AZ Family.

Judge Sherry Stephens also confirmed on Monday that the Arias re-trial will not end by Dec. 18, and instead go on until January. 

"We knew it," said courtroom blogger Jen Wood. "We knew it would go into January. We knew it would never end in December."

"The judge notified the jury that they probably aren't going to finish until January," she continued. "When in January we don't know. But they need to submit any concerns that have to the judge so they can go over that with the lawyers and make sure they can still retain a jury."