CLEVELAND -- The man guilty of killing 14-year-old Alianna DeFreeze faces the death penalty as his sentencing phase began in Cleveland court Wednesday.

Christopher Whitaker, 45, was convicted by a jury last week on all counts against him, including aggravated murder, rape and kidnapping.

Dr. Robert Kaplan was called to the stand Wednesday.

Kaplan, a forensic psychologist, testified that Whitaker is just short of having split personality disorder and that Whitaker's violent actions were a reactive manifest of his anger issues rather than planned behavior.

He also said Whitaker lost his mother and experienced domestic violence at a young age, which led to many of his problems. There are no police reports or evidence to prove Whitaker suffered instances of domestic violence.

Whitaker's defense team did not contest the charges against Whitaker, who admitted to the crimes and detailed them to investigators.

During opening statements of the sentencing phase, the defense said Whitaker would address the jury before they choose his punishment. The defense also gave multiple examples of the difficult life experiences Whitaker had growing up.

Instead, Whitaker's attorneys argued he was high when he killed Alianna. They also noted that Whitaker was remorseful and cooperative with police, but prosecutors countered that Whitaker made a choice to get high and that his crimes against Alianna were premeditated, because he had a variety of tools stored in the house where he tortured and killed her. Those tools, including a screwdriver, drill and knife, were displayed before the court during the trial.

Alianna went missing from a bus stop in the area of E. 93rd Street and Kinsman Road in January 2017. Her body was found inside an abandoned home on Fuller Avenue. Prosecutors say she had been raped, beaten and tortured prior to her death.