Jodi Arias Admits In Court She Killed Boyfriend

The woman at the centre of a sensational murder trial in Arizona has made a surprise appearance in the witness box.

Jodi Arias is charged with stabbing and shooting dead her on-off boyfriend in June 2008, in what prosecutors describe as a jealous rage.

She took the stand in a Phoenix courtroom for the first time on Monday, and quickly admitted she killed Travis Alexander in self-defence.

But she added that she also planned to take her own life.

"Did you kill Travis Alexander?" defence attorney Kirk Nurmi asked.

"Yes," she replied. "The simple answer is that he attacked me and I defended myself."

The decision to have the 32-year-old testify was unexpected because she faces the death penalty if found guilty.

Arias described how her idyllic childhood in California turned abusive at the hands of her parents when she was about seven years old.

She went on to describe abusive relationships with previous boyfriends.

She also said she initially denied being at the scene of the crime because she planned to commit suicide and never come to trial.

Prosecutors allege she stabbed and slashed Alexander nearly 30 times, slit his throat and then shot him in the face at his home, after he tried to end their relationship.

Jurors have been shown pictures taken by the couple, on the day of the killing.

The 30-year-old victim is pictured taking a shower.

Other more graphic and sexual images show the couple naked.

Police said the photos were time-stamped on the day of the murder and that Arias' bloody palm print and hair also were found at the scene.

Her trial, which began in early January, 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 they continued to see each other for sex up until Alexander's death.

Defence lawyers have depicted the successful motivational speaker as a liar and cheat who told Arias and other girlfriends he was a devout Mormon saving sex for marriage.

In reality, they claimed, he was seeing a lot of women at the same time.

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.

Every detail of the trial is being devoured on American cable TV, on the internet and via social media, with whole sites devoted to the defence and prosecution case.

Many see parallels with the long-running murder trial of Casey A nthony who was accused but ultimately acquitted of killing her young daughter.