Jodi Arias, the US woman found guilty of slaughtering her boyfriend in 2008 in a high-profile murder case, could face the death penalty after a jury ruled Wednesday that she was "especially cruel."

The 32-year-old, convicted last week of premeditated first degree murder for killing ex-boyfriend Travis Alexander, is on suicide watch after saying she would prefer a death sentence to life in prison.

The same jury that found her guilty deliberated for two hours before declaring that she fulfilled one of a statutory list of "aggravating factors" in the slaying.

Specifically, the jury members ruled that she was "especially cruel," meaning that the victim suffered pain or mental anguish, and that Arias was aware that her actions could cause that pain or anguish.

That paves the way for a possible death penalty in the next, sentencing phase of the trial, which has been followed closely by US media.

If not sentenced to death, she would be jailed for life with no possibility of parole for at least 25 years.

Arias had been on trial since January accused of murdering Alexander, 30, in June 2008 in a frenzied attack in which he was stabbed 27 times, shot in the head and had his throat slit.

Arias claimed she was acting in self-defense, but a jury found her guilty of premeditated murder, in a case watched by crowds outside the court in Phoenix, Arizona and carried live on US television.

Shortly after her conviction last week, Arias told a local TV station that she would rather be executed than locked up for life.

"I said years ago that I'd rather get death than life, and that still is true today," she told a Fox News affiliate. "I believe death is the ultimate freedom, so I'd rather just have my freedom as soon as I can get it."