Feb. 11, 2013 -- Accused killer Jodi Arias made the dramatic accusation in court today that her ex-boyfriend, Travis Alexander, told her he was sexually attracted to young boys and then became increasingly abusive toward her in the months after.

Arias said that in January 2008, she walked in on Alexander masturbating to pictures of young boys and that he confessed to being attracted to children. He then convinced her to sleep with him to cure him of his "deviant urges," she said.

"When I walked in, Travis was on the bed masturbating," she said. "He started grabbing at something on the bed,and I realized they were papers, and one kind of went sailing off the bed in the chaotic way paper falls, and it fell at my feet, and it was a photograph. It was a picture of a little boy... in underwear or briefs."

Arias, 32, said that she ran out of the house where she saw Alexander masturbating, drove to her house and threw up. Later she went back to Alexander's house so he could explain, and he told her he had a sexual interest in boys. He also told her he bought her boys' Spiderman underwear to wear during sex because of his interest in children, she said.

The claims have been part of the defense's strategy to portray Alexander as a "sexual deviant" who was controlling and abusive toward Arias, leading to their conclusion that Arias killed Alexander out of self defense.

She is on trial for murder and could face the death penalty if convicted.

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Arias said today that over the next couple of months, Alexander became increasingly abusive, pushing her and shaking her when they argued and when she suggested he seek mental help for his sexual interest in children.

She described a particularly violent episode during an argument in April 2008 in which Alexander threw Arias to the floor and kicked her in the ribs and in the hands.

"He told me he needed to borrow $200, and I didn't have it, and I had just lent him $699 a few days prior," Arias testified today. "He walked across the room and started shaking my shoulders and said, 'I'm f***ing sick of you' and slammed me on floor at the foot of his bed."

"I let out a yelp, sort of on impact, and he called me a b**** and kicked me, in the ribs, and that hurt for real, and he went to kick me again, but I put out my hand to block his foot and it clipped my hand and hit my finger," she said.

She claimed that the kick broke her finger and she held up her hand to show the courtroom how the ring finger on her right hand is permanently crooked from the kick.

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Arias said that she did not call police or seek medical attention because it would seem "disloyal" to Alexander, and that he had made her a splint of popsicle sticks after he calmed down. The incident allegedly occured two months before Arias killed Alexander in a violent attack that she claims was self-defense.

Arias's attorney, Kirk Nurmi, said in court today that Arias' testimony was helping to portray her as a "battered woman."

Arias' bold statements come during the third day of testifying, during which she described a string of sordid sexual behaviors Alexander allegedly made her participate in, including making her wear boys' Spiderman underwear while they had anal sex, paying her to dress up in a French maid costume while she cleaned his house and had sex with him, and giving him oral sex on her front porch.

"He wanted to drive up to the home, get out of the car, have me come out of the house and give him oral sex. He wanted to ejaculate on my face and drive away without saying a word," Arias said. "The first occasion was just like he described, but the second occasion, he dropped something near me and got in his car and left. I picked it up and it was Toblerone."

"So he ejaculated on your face and threw you some candy?" Nurmi asked Arias.

"Pretty much," she said.

Arias also said that while sleeping next to Travis at his home one night, she awoke to find him on top of her, having sex with her, without her consent.

From the time they met in the fall of 2006 until the beginning of 2007, Arias and Alexander had an intense sexual relationship that included anal and oral sex as well as phone sex and pictures of Alexander's penis, but they avoided intercourse because they were both practicing Mormons. Pre-marital intercourse is prohibited for Mormons.

In 2007, Arias said she spent a weekend at Alexander's house and before going to bed the pair prayed to follow the church's law of chastity more closely. Later that night, she awoke to find Alexander having sex with her.

"I woke up and he was on top of me, and had already penetrated and started having sex with me," she said.

"He was on top of me, on my stomach, and was heavy, so I started to squirm a little and began to quicken... his pace, and I either pushed him off or got out from under him, and he rolled over and pulled me on top of him and started pushing my head and shoulders under the covers. I presume for oral sex. No words were spoke."

Arias admitted that she did not tell Alexander to stop, saying that she didn't want Alexander to be upset with her. He had complained of feeling sexually frustrated previously, she said.

She continued to have a sexual relationship with him after that until June 2008, when she had sex with him and then killed him at his home in Mesa, Ariz.

Before today's testimony, the prosecution petitioned Judge Sherry Stephens to ban from the trial the allegations of masturbating to boys' pictures, saying there was no evidence to support Arias' claims. Police found no photos of young boys on Alexander's computer or in his home, and found no evidence that would indicate he tried to erase anything on his hard drive.

Jodi Arias Alleges Travis Alexander's Kinky Sex

Additionally, they claim that Arias gave two different accounts of the incident, telling one expert that the images were on Alexander's computer, and later testifying at a hearing that that they were hard copies of photos spread out on his bed.

But Stephens ruled on Thursday that she would allow the testimony today.

"I'm surprised the judge let this in," said ABC News legal analyst Dan Abrams. "This is incredibly inflammatory and it fits conveniently into the defense's theory."

"This is a risky move for Jodi Arias because if these jurors don't believe her already, this is just going to make them angry at her," he added.

Arias' defense team has also tried to include 10 letters that they say Alexander wrote as evidence of his attraction to boys.

Handwriting experts for the defense claim that the letters were written by Alexander, while experts for the prosecution say they were forged.

The letters may be admitted into testimony later this week.

The defense may also play an audio recording of a phone conversation between Arias and Alexander from 2008 that is sexual in nature.