As he delivered his opening statement, prosecutor Juan Martinez displayed a photo of the slit throat of Arias's boyfriend and victim Travis Alexander, who also was shot and suffered about 30 stab wounds in his Mesa home more than six years ago.
Prosecutors say Arias killed Alexander in a fit of jealousy and rage after he broke off their relationship and wanted to see other women.
"It's up to you to write the final chapter to this story," Nurmi told the new jurors deciding whether Arias should live or die.
The 34-year-old Arias was convicted of murder last year, but that jury deadlocked on whether to give her the death penalty or life in prison.
The start of the sentencing retrial was less of a spectacle than the initial case in early 2013, when onlookers from around the country traveled to Phoenix and lined up outside court for the trial that became a tabloid TV sensation.
The tumultuous relationship of Arias and Alexander became a major part of the obsession over the case as intimate details of their time together were revealed in the courtroom.
The first trial was broadcast live, but Judge Sherry Stephens imposed restrictions this time. Cameras are allowed at the retrial, but none of the footage can be broadcast until after it's finished.