Arias said she lied because she was ashamed of having killed her lover, Travis Alexander, in self-defense. Arias also said she didn't want details of their raunchy sexual relationship to be revealed, in part because Alexander lived a public life as a devout Mormon saving himself for marriage but privately was seeing multiple women romantically.
Arias is charged in the June 2008 death of Alexander in his suburban Phoenix home. She says she fought for her life after Alexander attacked her, while authorities say she planned the killing in a jealous rage. Testimony has been ongoing since early January. Arias returns to the witness stand for an 11th day on Tuesday.
Arias first told authorities she knew nothing about Alexander's death, then later blamed it on masked intruders before eventually settling on self-defense.
She told Alexander's friends and family the same stories after her arrest, even sending 20 white irises to the victim's grandmother, along with an 18-page letter to his family, expressing sympathy.
Prosecutor Juan Martinez then played a video clip for jurors of an interview Arias did with CBS's "48 Hours" in July 2008 while she was in jail.
"Travis' family deserves to know what happened," Arias said on the tape.
"They did deserve to know what happened but did they deserve that lie?" Martinez asked Monday, noting at the time of the interview that she was still sticking to the story about the intruders killing Alexander.
"I guess not," Arias replied.
Martinez also noted that Arias immediately began planning an alibi after she killed Alexander, leaving a message on his mobile phone and going to visit a man in Utah just hours after the attack.
When Alexander's body was found days later, Arias began making calls—to police, to friends, to her Mormon bishop—all to figure out what authorities knew and whether "anybody was onto you," Martinez pointed out.
"Partially, yes," Arias said, but she again repeated that she didn't recall much from the day of the killing.
Throughout the day, Martinez hammered her over the lies, prodding her to agree it was all part of trying to avoid going to prison.
"I don't know, I was trying to kill myself," Arias said.
She previously testified she tried to commit suicide while in jail, but she nicked her wrist with a razor and it stung, so she delayed it.
"Can you imagine how much it must have hurt Mr. Alexander when you stuck that knife into his chest," Martinez snapped back loudly.
Defense attorneys immediately objected, and the line of questioning changed.
The trial has been a made-for-the-tabloids drama, with tales of lurid sex, lies and death, nude photos and accounts of a salacious relationship. Arias says she and Alexander dated for about five months, then broke up but continued to see each other for sex while Alexander grew more abusive.
However, she never reported any abuse to authorities, and jurors haven't heard from any witnesses or seen any evidence supporting her statements that Alexander had a history of violence.
On Monday, she said she told an ex-boyfriend how Alexander had attacked her and choked her into unconsciousness after the man noticed bruises on her neck and arm.
Martinez asked if the man could corroborate her story.
"Yes," Arias replied sheepishly.
Martinez then snapped back, asking if she was aware the man told authorities he had no recollection of it.
Defense attorneys immediately objected, leading to a private meeting with the judge and attorneys. Martinez then moved on.
Arias has said Alexander invited her to his Mesa home on the day of the killing for sex.
His body was found in his shower about five days later. He had been shot in the forehead, suffered 27 stab and slash wounds and a slit throat.
Of the day of Alexander's death, Arias says she doesn't recall much but remembers him in a rage, body slamming her and chasing her around his home.
She said she grabbed a gun from his closet, and fired it as they tussled, but she didn't know if she hit him. She says she doesn't recall stabbing him.
According to court records, however, she told police before her trial began that Alexander was unconscious after she shot him, but then "crawled around and was stabbed." She says she remembers putting a knife in the dishwasher and disposing of the gun in the desert as she drove from Arizona to Utah.
Arias' grandparents reported a .25 caliber handgun stolen from their Northern California house about a week before the killing—the same caliber used to shoot Alexander—but Arias says she knows nothing about the burglary. She says she brought no weapons to Alexander's home on the day she killed him, undercutting the prosecution's theory of premeditation.