Updated

Alleged killer Jodi Arias took the witness stand Monday claiming she was no liar – though she acknowledged telling a lie or two.

The prosecutor hammered Arias, who faces murder charges in the death of her ex boyfriend, about her repeated lies to authorities. He say her memories seemed crystal clear during direct examination by her attorneys, yet seem to have diminished greatly under his questioning.

Arias admitted lying to police in the early stages of the investigation because she was ashamed of having killed her lover, Travis Alexander, she says in self-defense. Arias also said she didn't want details of their raunchy sexual relationship to be revealed.

Yet prosecutor Juan Martinez noted her memory of crucial details seems surprisingly hazy under his questioning, compared to her detailed recollections when questioned by her own attorneys.

"I reviewed those things, so I memorized them," Arias said of her answers during direct examination.

"So everything that you have told us then in this case is based on what you have reviewed?" Martinez snapped.

"Not everything," Arias replied.

Arias is charged in the June 2008 stabbing and shooting death of Alexander in his suburban Phoenix home. Arias says she was forced to fight 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. Monday was Arias' 10th day on the witness stand.

Arias first told authorities she knew nothing about Alexander's death, then later blamed it on masked intruders before eventually settling on self-defense.

Martinez noted she repeatedly lied to authorities, specifically during two interrogations in July 2008, in order to avoid being charged in the killing. She agreed, but also said she was too ashamed to admit the truth.

"The whole interview was a lie, right?" Martinez asked.

"Not the whole interview," Arias said.

"Anything having to do with responsibility for this crime was a lie right?" Martinez prodded.

"Yes," Arias replied.

Martinez continued hammering her with questions over why she lied, noting it was solely 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 after her arrest, 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.

Alexander was shot in the forehead, suffered 27 stab and slash wounds and had his throat slit. His body was found in the shower of his Mesa home about five days after the June 4, 2008, killing.

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 previously 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 on her way to Utah. And she immediately began planning an alibi.

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 claims to know 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.

Based on reporting by The Associated Press.

Follow us on twitter.com/foxnewslatino

Like us at facebook.com/foxnewslatino