(Please note that story contains graphic details.)

By Tim Gaynor

PHOENIX (Reuters) - A woman charged in Arizona with capital murder for stabbing and shooting her lover to death laid out in graphic detail on Monday what she said was the first time she had sex with him, an experience she said began while she was still asleep and left her concerned about her spiritual health.

Lawyers for Jodi Arias, whose testimony has gripped viewers across the United States, argue she acted in self-defense when she killed Travis Alexander, who was found in the shower of his Phoenix valley home, shot in the face, stabbed 27 times and with his throat slit.

Prosecutors say Arias killed Alexander in a fit of jealous rage.

"We fell asleep, and I woke up and he was on top of me. He had already ... started having sex," Arias, a petite woman with long brown hair, said in a fourth day of testimony in an Arizona courtroom where she is on trial accused of murdering Alexander in 2008, months after that encounter.

Arias could face the death penalty if convicted, and in questioning her about the pair's sexual experiences, her lawyer appeared to be continuing groundwork for a defense centered on a pattern of abuse they say she experienced in the relationship.

She told the court that when she woke up in 2007 several months after they had begun dating to find Alexander having sex with her, she did not feel unsafe. But Arias, who said she converted to Mormonism at Alexander's behest, was worried about the "spiritual consequences" of the act.

"I wanted to comport with the law of chastity because I believed that our relationship would be blessed if we did that," she testified, dressed in a light wool blouse and eyeglasses.

Her counsel says Arias killed Alexander, whom she met at a legal insurance convention in Las Vegas in 2006, in self defense after their relationship turned abusive.

Arias also told the court how even after that sexual encounter she traveled in 2007 with Alexander to New York state where they visited a Mormon religious site as well as Niagara Falls, as it was on a list of "a thousand places" he wanted to see before he died.

Arias, 32, said she took the trip despite believing, after she discovered text messages from other women on his cellphone, that Alexander had been unfaithful to her.

She broke up with him only on their return to California - where she lived - because the trip had already been paid for and she had low self esteem.

"I didn't have a lot of self esteem, I was kind of doormat ... I knew (the) relationship couldn't continue. I was waiting for the right moment."

In testimony last week, Arias painted a picture of a charged relationship with Alexander that at times caused her physical and emotional pain and at one point made her feel like a "used piece of toilet paper."

Alexander, 30, had been dead for five days when he was found. His death was connected to Arias after sexually explicit photos were found on the memory card of his camera.

(Reporting by Tim Gaynor; Editing by Cynthia Johnston and Steve Orlofsky)