"You have a duty, and that duty really means that you actually do the honest, right thing, even though it may be difficult," he said. "And in this case ... the only thing you can do based on the mitigating circumstances and their lack of, is to return a verdict of death."
During the trial, Arias claimed she killed Alexander in self-defense after he attacked her. After the guilty verdict, she told a local television station that she had no interest in life in prison.
"I said years ago that I'd rather get death than life, and that still is true today," she told Phoenix television station KSAZ. "I believe death is the ultimate freedom, so I'd rather just have my freedom as soon as I can get it."
The penalty phase of the trial took a sudden break Monday, when the judge said that proceedings could not continue and that Arias would make the statement to the jury.
The adjournment followed Judge Sherry Stephens' dismissal of a defense motion for a mistrial and ended a session in which the defense called no witnesses on Arias' behalf. Also denied was a second request by Arias' lawyers to withdraw from the case.
Arias, who testified for 18 days during the trial, was not cross-examined after her Tuesday statement, which Stephens said was not under oath.
For Arias to be sentenced to death, the jury's decision must be unanimous. In the case of a deadlock, a new jury would be chosen for this phase only.
If Arias is given a sentence of death, she would be the fourth woman on death row in the state.