Jodi Arias admits killing Travis Alexander, but testified in court this week that her ex-boyfriend was abusive and that she did what she had to in self-defense.
The sensational murder trial in Arizona was not expected to feature Arias herself in the witness box, but she elected to take the stand in her defense.
Police and prosecutors don't buy it. Jodi Arias is charged with shooting Travis Alexander in June 2008, in what authorities describe as a jealous rage.
She also stabbed him repeatedly and slit his throat.
Yet took the stand in a Phoenix courtroom for the first time on Monday, and quickly admitted she killed Travis Alexander, but swore she had no choice.
She added that she also planned to take her own life.
"Did you kill Travis Alexander?" defense attorney Kirk Nurmi asked. "Yes," she replied. "The simple answer is, he attacked me and I defended myself."
The decision to have the 32-year-old testify was unexpected because she faces a tough cross-examination - and the death penalty if found guilty.
Arias went on to describe how her idyllic childhood in California turned abusive at the hands of her parents, then continued thanks to abusive boyfriends.
As for why she initially denied being at the scene of the crime, she explained that she planned to commit suicide and thus never come to trial.
Prosecutors have portrayed Arias as a jealous ex-girlfriend who could not let go of Alexander and stalked him until she finally snapped and killed him.
Friends say he feared dating an axe murderer, and the state has cited pictures taken by the couple looking happy together on the day of the killing.
The 30-year-old victim is pictured taking a shower. Other more graphic and sexual images show Jodi Arias nude, possibly hurting her abuse claim.
Her trial has also featured shocking police photographs from the crime scene in Mesa, including several of Alexander's badly wounded body.
The couple met at a Las Vegas conference in 2006 and dated for five months, but continued to see each other for sex up until Alexander's death.
The successful motivational speaker, who she killed in 2008, is being portrayed not merely as a victim, but as a liar and cheat by the defense.
He allegedly told Arias and other girlfriends he was a devout Mormon saving sex for marriage, while at the same time dating several women at once.
Many see parallels with the long-running murder trial of Casey Anthony who was accused but ultimately acquitted of killing her young daughter.