A beautiful young woman is about to go on trial for her life, accused of the savage, frenzied murder of her ex-boyfriend.

"I know that I'm innocent. God knows I'm innocent, Travis knows I'm innocent."

She's talking about Travis Alexander, a popular motivational speaker she dated for five months.

30-year-old Travis Alexander was a natural performer who used his vivid personality to energize and inspire sales forces. He created a madcap character, dressed in a black wig and dark sunglasses, as a comic element in his presentation.

The steamy affair with Jodi Arias came to an end in 2007 when she says she discovered he was cheating. "It wasn't very pretty. Breakups are never easy but that sort of signified the end of out relationship," Arias tells INSIDE EDITION in a jailhouse interview.

Last June Travis was brutally murdered.

Travis Alexander was found dead in his shower at his luxury home in Mesa, Arizona. He had been shot in the face and stabbed 27 times. His throat was slit from ear to ear. Police found a camera at the crime scene. On it, provocative, naked photographs of Jodi and Travis taken the day he was viciously murdered.

Another photograph showed Travis seriously wounded and bleeding.

Prosecutors say 28-year-old Jodi went to her former boyfriend's home for a final tryst, took the provocative photographs, then murdered him.

Authorities even have Jodi's palm print in his blood.

INSIDE EDITION's Paul Boyd met Jodi Arias for a jailhouse interview.

"I absolutely did not kill Travis Alexander. I had nothing to do with his murder. I didn't harm him in any way," she says emphatically.

Arias dropped a bombshell, describing for the first time what she says happened the day of the murder.

"I witnessed Travis being attacked by two other individuals," she says. Arias says she could not pick out the individuals in a police line-up. "They came into his home and attacked us both."

Arias says a man and a woman, both wearing masks, burst into the house and attacked both of them. She claims she fled, but was too terrified to call the police.

When INSIDE EDITION asked why she would not have immediately called the police, Arias says, "I'm not proud that I just left my friend there to be slaughtered at the hands of two other people, I'm not proud of that at all."

She goes on to say that she understands "that everything, all of the evidence against me, is very compelling." However, "In a nutshell," she says, "Two people took Travis's life. Two monsters."

Jodi Arias is sticking to her story that two mystery killers murdered her former boyfriend, and she's convinced a jury will believe her.

"No jury is going to convict me...because I am innocent and you can mark my words on that. No jury is going to convict me."