A jury took only three hours to decide that Jodie Arias was guilty of pre-meditated murder, but her legal team is now fighting to prove she does not deserve the death penalty. NBC's Diana Alvear reports.

The Phoenix jury that convicted Jodi Arias of first-degree murder last week needed only a few hours Wednesday to decide that her conduct was so extreme that it could merit the death penalty.

Jurors announced that they had found that Arias had been "especially cruel" in killing Travis Alexander in 2008. That would constitute an aggravating factor that Arizona law says could justify the death penalty.

The jury will return to court Thursday to hear new testimony and arguments as it begins deciding whether Arias should die or should spend the rest of her life in prison.

"The last thing that Mr. Alexander felt as he lay there and as he was looking up was this knife and this woman and this blade coming towards him," Deputy Maricopa County Atorney Juan Martinez, the prosecutor, told jurors.

"And it was only death that relieved that pain, and it was only death that relieved that anguish," he said. "And that is especially cruel."

Arias' attorney, Kirk Nurmi, argued that Arias' conduct wasn't "a matter of cruelty" on its own. Instead, he said, jurors had to be convinced that Arias went "beyond (the) normal cruelty that's inherent in any first-degree murder."

The sentencing phase of the trial had been scheduled to begin last Thursday, but it was postponed without an official explanation. Sheriff's deputies arrested an 18-year-old man the same day and charged him with threatening to bomb the courthouse where Arias was tried.

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