Ariz. Woman Faces Death Penalty in Boyfriend's Slaying

Tonight we begin with a twisted tale of romance gone deadly wrong. Today, opening arguments began in the shocking murder trial of a 32-year-old woman who stands accused of an unbelievably violent... See More

Tonight we begin with a twisted tale of romance gone deadly wrong. Today, opening arguments began in the shocking murder trial of a 32-year-old woman who stands accused of an unbelievably violent crime. Slashing, stabbing and shooting her one-time boyfriend. Since her arrest, her story of what happened that night has shifted dramatically, and soon, her life could depend on which version a jury believes. Here's abc's ryan owens. Reporter: She may have won this jailhouse christmas carolling contest, but jody arias may have a much tougher time winning over a jury. This is not a case of whodunit. The person who committed this killing sits in court today. Reporter: The 32-year-old who faces the death penalty cried today as prosecutors laid out their opening arguments, detailing for the jury in phoenix, arizona, how she allegedly murdered her one-time boyfriend travisxander in june of 2008. Prosecutors say the soft spoken arias attacked travis in a jealous rage as he showered. Stabbing him 27 times, slitting his throat, and then shooting him in the head. Mr. Alexander did not die calmly. He fought. Reporter: Arias also wiped away tears as her attorney painted a different picture, of an abused woman who was forced to kill in self-defense. And a victim who claimed to be a devout mormon but was really a sexual deviant. In just those two minutes, jody had to make a choice. She would either live or she would die. Reporter: This twisted tale has everything. Today, the jury saw steamy photos of the victim in the shower just before he was killed. There's also a sex tape of the couple together, and a series of jailhouse interviews when arias repeatedly denies she killed anyone. I didn't hurt travis. I would never hurt travis. I would be shaking in my boots right now if I had to answer to god for such a heinous crime. Reporter: The two met at a work conference six years ago. Jody says they fell in love and traveled the country. Family members say travis was a devout mormon and didn't believe in premarital sex. They say he lost his virginity to jody. She even converted to mormonism to show her devotion, but their romance only lasted a few months. Travis tried to break it off, telling his friends -- she's not who I want to marry. There's nothing about her that i see in marriage material or wife material. Reporter: Travis's friends say jody stalked him in the months leading up to the murder, after she found out he had started dating other women. One night his tires were slashed. And it obviously wasn't an accident. And we all knew it was jody. That had done it. But can't prove it. Reporter: But prosecutors say they can prove a lot, starting with the fact that this accused murderer can't keep her stories straight. I had no part in it. Reporter: Two weeks after those jailhouse interviews when she denied being at travis's house the night of the murder, jody arias told the tv show ""inside edition"" something quitt. I witnessed travis being attacked by two other individuals. Who? I don't know who they were. I couldn't pick them out in a police lineup. Reporter: That story didn't hold up long either, especially once detectives found a camera in travis alexander's washing machine. Police believe jody deleted a series of photos from it, then literally tried to wash away the evidence. But forensic teams recovered the camera's memory card. What was on it, today the jury saw a series of pictures of the couple having sex the day of the murder. Mr. Alexander was very much alive, and yes, they were going at it. Reporter: But that's not all. Next, the jury saw a series of pictures taken a few hours later of a naked travis posing in the shower. Then seconds after that, a couple of pictures that looked like they were accidentally snapped showing travis's bloody body, and then after it appears someone dropped the camera, a snapshot of jody arias dragging his body. Which brings us to her latest story, the one her attorney began telling the jury today. Had jody not chosen to defend herself, she would not be here. Reporter: Jody now says she did kill travis, but only in self-defense. She says he got enraged when she dropped his new camera. Yes, the one with all of the evidence on it and then threatened to kill her. In fact, she claims he was sexually and physically abusive to her throughout the relationship. Her attorney showed the jury this t-shirt she says illustrates travis's sense of ownership of jody. There's not any evidence of all the women that travis has ever dated in his life, not one of them has ever come forward and said when our relationship broke up, he was angry, he showed violence. It was just not in his nature. It's just not his personality. And the evidence is very clear that he was obviously in a defensive de. Reporter: Still, it's up to the prosecution to prove this wasn't a case of self-defense. The law in arizona does make it tougher for prosecutors to effectively disprove self-defense, but with these facts, I don't think that's going to be particularly difficult. Reporter: Jody arias remains as confident today as she was the day she was arrested. No jury is going to convict me. Reporter: Why not? Because I'm innocent and you can mark my words on that one, no jury will convict me. Reporter: The prosecutor ended his arguments by playing that clip for the ry. It will be their job to decide if the accused murderer who keeps changing her tune -- ♪ a thrill of hope ♪ Reporter: Is guilty and whether she should die for the crime. I'm ryan owens for "nightline" in phoenix.