From the start of their courtship, friends say, Jodi Arias and Travis Alexander had a potent chemistry.
Friends said the connection was instant when they met.
"She was really excited about the relationship. She loved how funny he was, how much fun they would have together. Travis loved to take adventures and do different things," said Alexander's friend Sky Lovingier Hughes.
Although they lived in different states -- he was in Mesa, Arizona, and she was in Palm Desert, California -- they maintained a long-distance relationship for a few months and would meet at the Murrieta, California, home of Lovingier Hughes and her then-husband Chris Hughes.
But Alexander’s friends told "20/20" that they started noticing red flags with Arias early on in the relationship. They said they’d alerted Alexander to their concerns and that they'd even grown concerned for his safety as things grew toxic and volatile between the two.
"I started seeing things that were just disturbing," Lovingier Hughes said. "I said, 'Travis, I'm afraid we're gonna find you chopped up in her freezer.' ... From very early on, she was completely obsessed with him."
Alexander was found dead on June 9, 2008, more than a year after he and Arias had connected, and after those close to Alexander believed the relationship was finally over. He'd been stabbed multiple times and had a gunshot to the head.
The murder was a shock to friends and family, and the scintillating details that came out of the case kept the story in the media for years as Arias, authorities’ prime suspect, awaited trial. She was eventually convicted of his murder.
Arias and her lawyers are now appealing that conviction, alleging many improprieties including prosecutorial misconduct. The state has denied those allegations in its response and says that Arias received a fair trial.
Steven Alexander, Travis' brother, said he was not too concerned about her latest efforts to get out of prison.
"None of it affects the fact that she murdered my brother and she's admitted to it," he said.
Love at first sight
Arias was looking for opportunities with a network marketing company called Pre-Paid Legal Services, Inc. when she met Travis Alexander at a company convention in Las Vegas in September 2006.
The two hit it off, with Alexander even inviting Arias to the company's formal executive dinner as his guest.
"She's beautiful. She's friendly, has long, blonde hair. Cute figure. She was very sweet," Lovingier Hughes said of Arias. "During the dinner, they just talked the whole time. She seemed to like him as much as he liked her."
Hughes, another close friend of Alexander's, said Alexander was smitten. After the dinner, Alexander and Arias talked with each other until 4 a.m.
"The next morning, he tells me that he's found his wife and this is the girl that he wants to marry," Lovingier Hughes said.
"It was cute, you know? I mean, I was, like, 'OK. I mean, like, good for you, Travis.' It was cute to watch," Hughes said.
After the convention, once Alexander and Arias began seeing more of each other, they traveled to popular sites in the Southwest. Arias documented online their time together, posting photos to social media. In an email to Hughes, Alexander shared how deeply he cared for Arias.
"I went from intrigued by her to interested in her to caring about her deeply to realizing how lucky I would be to have her as part of my life forever. ... She is amazing. It is not hard to see that whoever scores Jodi, whether it be me or someone else, is gonna win the wife lotto," Alexander said in that email.
There was trouble, however, in the blossoming romance. Alexander was deeply involved in his faith and she was not Mormon. Unbeknownst to friends, the two were having premarital sex, breaking one of of the most important tenets of the Mormon faith.
Colleen McDannell, a professor of religious studies at the University of Utah, told "20/20" that for Mormons, sex and sexual activity outside of the bounds of marriage are forbidden.
"The law of chastity basically says your body is a sacred space. Your body was given to you by God. It's not just yours, it's not just your decisions to do with as you will. God has given this to you and you must respect it," McDannell said. "And, Latter-Day Saints believe that because marriage is so important and so intense and sexuality is so much a part of that, that you need to preserve those sexual expressions for your spouse. So before you marry and after you marry, you have to keep yourself sexually pure."
Being true to his religion was incredibly important to Alexander, and the guilt he felt about their relationship started to weigh on him, friends said.
"He was always incredibly strong in the church but after meeting Jodi, some of the conversations were about the challenge of morality, because this girl is in his life," another friend, Dave Hall, said.
Travis Alexander battles with his Mormon faith
Alexander maintained a blog called "Travis Alexander's Being Better Blog." In a post, he wrote candidly about his early life.
For example, he wrote about a difficult childhood while growing up in Southern California with his parents, who were addicted to drugs at that time.
"It was a very tough life living with our mother," Steven Alexander said. "We kinda fended for ourselves. ... [Instant noodles] was the main source of nutrition."
In his blog, Alexander wrote: "When you sleep, for four days with a house full of kids, there isn’t any food cooked. We would eat what was there but before long what was edible would be eaten or rot and then what was rotten would be eaten too."
Alexander's grandmother eventually took him and his siblings in, and began clothing and feeding them, Steven Alexander said.
"Our grandmother was a saint. I mean, she was the greatest woman. ... She got us all in church, you know, pointing us in the right direction," he said.
Soon after Alexander met Arias, he sent missionaries to her home. He also talked about the Book of Mormon with her and quoted scripture to her. Within months of their meeting, Arias converted to Mormonism. He baptized her.
"It was emotional. It was spiritual. It was powerful … it's a feeling that … like everything just comes right into alignment and nothing can go wrong," Arias said in a 2008 interview with ABC News.
Hughes said that Alexander still struggled and suffered with guilt over the fact that he and Arias were having sex.
"They're both sinning in the eyes of his church. Travis wanted to marry a virginal, pure Mormon girl, and by having sex with him, Jodi eliminated herself as ever being marriage potential for Travis," said Shanna Hogan, an author and journalist who wrote the book "Picture Perfect: The Jodi Arias Story."
McDannell told "20/20" that marriage was the foundation of the Mormon faith and that it was very important for members to meet each other and to marry in the temple.
"That enables them then to live in the other life eternally and eventually to spiritually progress," she said.
Jodi Arias' troubling behavior
Early on, Alexander's friends began noticing odd behavior from Arias, particularly her infatuation with their friend.
"One night we're all in the hot tub and there's four of us. You know, this is a time to chat and hang out. Well, Jodi is, like, climbing on Travis while we're trying to have this conversation," Hughes said.
"She was all over him. I mean, like eighth-graders whose parents are out of town, like, straddling his lap and sucking on his neck. And Travis just kept pushing her off and he's like, 'Jodi...get off me. Like, what are you doing?' And I look at Chris [Hughes] and I'm like, 'Does she not realize we're sitting here?'" Lovingier Hughes recalled. "This is around the time where she became very possessive of him."
"That was one of those nights where, like, she’s weird. You know, like this is weird," Hughes said.
Alexander's friend Clancy Talbot said Arias was very possessive.
"She just had to sit right by him. She didn’t appreciate when he was talking to another female. She didn’t like the fact that if there was anyone that didn’t know that they were together. She wanted to make that clear," Talbot said.
As his friends got to know her better, they said they grew increasingly creeped out by Arias' behavior. Lovingier Hughes said that Arias would follow Alexander to the bathroom and stand outside the door or eavesdrop on his conversations. Hughes said she went through Alexander's cellphone on multiple occasions as well as his emails and social media accounts. Lovingier Hughes added Arias would go so far as to forward emails between Alexander and other women to herself.
Hughes said that he and Lovingier Hughes talked with Alexander about their concerns. One day, they said they sat him down and told him they thought Arias was dangerous.
But Hughes and Lovingier Hughes said Alexander rebuffed their concerns, telling them he thought Arias was good and sweet and that he really liked her.
"All of a sudden I got this cold feeling over me and I knew she was outside our door. ... I mouthed to them and pointed at the door and I said, 'She's out there,'" Lovingier Hughes said.
Alexander didn't believe them but when he opened the door suddenly, he found Arias standing on the other side, Hughes and Lovingier Hughes said. Lovingier Hughes described the look on Arias' face as "evil."
"There was a rage in her eyes. ... Sky and I are very frightened at this point. She might burn down our house, you know, with all of us in it," Hughes said.
The romance appears to end
After five months together, Alexander broke up with Arias. Weeks later, she moved to Mesa, where he was living. His friends were baffled.
His friends said Arias would show up to his house unannounced and let herself in through the garage door because she knew the code, according to Brian Skoloff, who co-wrote a book about the Arias case called "Killer Girlfriend: The Jodi Arias Story." Skoloff said Alexander told friends she'd even snuck into his house through a doggy door.
"Sometimes Travis would be angry and other times he would jump into bed right with her and they would have sex," Hogan said.
Meanwhile, Alexander began dating a woman named Lisa, Lovingier Hughes said. Arias, she said, would try scaring Lisa by knocking on her door and windows before running away.
Alexander’s friends said his tires were slashed on two occasions while he was dating Lisa, and that he and his friends believed Arias was the one behind it. When Alexander confronted her with his suspicions, she denied it, Hogan said.
By April 2008, after living in Mesa for about eight months, Arias returned to her family in Yreka, California.
"I was excited and Travis was excited," Lovingier Hughes said. "He said, 'I'm getting, I'm getting my life back. Like, this is a whole new start. She's gone.'"
Despite this change, unbeknownst to his friends, Arias and Alexander continued communicating via phone and texts and engaging in phone sex. Steven Alexander said Arias was his brother's "kryptonite."
But in May 2008, although the reasons were unclear, Gchat and text messages revealed the two were in the midst of a huge fight, according to Jane Velez-Mitchell, author of "Exposed: The Secret Life of Jodi Arias."
At one point, Alexander wrote: "You don't know what horror you have caused me."
"It wasn't really my intention to harm you," she responded.
He later called her a sociopath and "the lowest of the low."
Travis Alexander vanishes before trip to Cancun
In early June 2008, Alexander had plans to attend a company retreat in Cancun, Mexico, with a Mormon woman he was pursuing named Mimi.
The Hugheses had already gotten to Cancun and were trying to plan activities for when Alexander and Mimi arrived.
"I'm calling him and I'm texting him, 'Do you wanna do this? Do you wanna do this?' He wasn't responding," Hughes said.
When Alexander missed a conference call that he was supposed to be leading, the Hugheses grew worried and left him a voicemail.
"I said, 'T-dogg, you better be dead, bro.' Yeah, like I was joking. 'Call me back.' You know, 'Why are you dissin' me? Why aren't you calling me back?' I said to Sky...'something's wrong,'" Hughes said.
By June 9, 2008, it had been five days since his friends had heard from him. Mimi, who hadn’t left for the trip yet, and two others headed to Travis Alexander's home. A friend gave them the garage code to get them into the house, where they found one of his roommates named Zach Billings.
"They ask him, 'Hey, have you seen or heard from Travis?' He said, 'No. He's in Mexico.' And Mimi said, 'He's not in Mexico. I'm supposed to go with him to Mexico tomorrow,'" Lovingier Hughes said.
Billings opened the door to Alexander's room and entered, finding a puddle of blood on the carpet. He continued down the hallway to the bathroom, where he discovered Alexander's body crumpled up in the shower. The friends then called 911.
When Mesa Police detective Esteban Flores arrived on the scene, he told "20/20" that blood was everywhere.
"The first thing I thought was there was a major struggle in here. ... That it was deeply personal," Flores said. "Somebody knew him. Somebody wanted him dead. ... Somebody wanted to make sure that he was dead."
Authorities later determined that Alexander had been dead for days. He had been stabbed at least 27 times, his throat had been cut ear to ear and he had also been shot in the head.
Police found a bloody palm print outside of Alexander’s bedroom, long brown hairs on the floor and walls of the bathroom that only he used and a camera in the home’s washing machine.
When the Hugheses got the news, Chris Hughes said, "I remember just saying -- almost howling -- 'no, no, no, no, no' and 'Oh my gosh. How did this happen?'"
"It was just shock. I couldn't feel anything. I was sitting in the room, by myself, and it hit me that Travis was gone," Lovingier Hughes said.
Arias speaks to Mesa investigators
Within hours of Alexander's body being found, Arias called the police to ask about the case.
Flores said Arias told him that she'd spoken briefly to Alexander the day he was killed as she was driving to Utah to see a new guy she was dating. During their conversations, Flores told Arias that her name had come up repeatedly during the investigation.
"She was a stalker. She was an ex-girlfriend and she wouldn't leave Travis alone," he said Alexander’s friends had told him.
Arias denied being in Arizona at the time of Alexander's slaying, he said.
When she went to Arizona for Alexander's memorial service, she agreed to be fingerprinted by the police.
Investigators Discover Shocking Evidence
Computer forensic investigators then made a shocking discovery. They had analyzed the memory card of the camera they found in Alexander's washing machine and found photographs of him and Arias timestamped from the day of the murder, Flores said.
Authorities later learned that the blood from the palm print belonged to both Alexander and Arias. Flores and police traveled to Yreka, California, to arrest her.
During her police interrogations, Arias tried to explain why she had arrived a day late to Utah to see her new love interest. She had been expected on June 4, but arrived a full day later. She told police that her phone had died and she'd gotten lost on the road.
Ryan Burns, the man she was visiting in Utah, told police he'd tried to reach her three or four times and that each time the call had gone to voicemail.
Flores learned that a .25-caliber gun had gone missing from the home of Arias' grandparents about a week before the killing. The caliber of the grandparents' gun matched the caliber of the bullet casing that had been found on Alexander's bathroom floor.
As he questioned her, Flores showed Arias graphic photographs of her and Alexander just hours before he'd been killed. Arias continued to deny any involvement in the killing.
"No matter how much evidence I would tell her about, she was not going to admit that she was even there," he said.
The next day, after a night in jail, Arias admitted to investigators that she had been at Alexander's home the day he was killed.
Arias claimed that she'd arrived at 3 a.m. and that they'd slept and had sex. She claimed that later on, while she was taking photographs of him in the shower, they were attacked by two masked intruders -- a man and a woman -- who were bent on killing Alexander. She said that one of the masked intruders had told her to leave and threatened to kill her family if she ever mentioned the incident to anyone.
Authorities didn't believe her story. She was charged with first-degree murder in Alexander's death.
Arias remained in prison for more than four years while awaiting trial. In January 2013, her death-penalty trial started.
Arias takes the witness stand in her trial
On the witness stand, Arias told the court an entirely different story than the two previous ones she'd told investigators. She testified to killing Alexander but claimed that it was done in self-defense after he became angry when she dropped the camera that authorities later found in the washing machine. She claimed Alexander had abused her on several previous occasions.
She also claimed that she'd found him masturbating to a photograph of a child.
"There was absolutely no proof that Travis had ever been physically abusive with her or anyone in his life in the past. … None of these claims were ever proven. Police never found child pornography anywhere in Travis’ house," Skoloff said.
"Her mission was basically to murder my brother again for a second time by destroying his reputation," Steven Alexander said. "The self-defense story was just...a joke. My brother didn't even own a gun."
In May 2013, the jury found Arias guilty of first-degree murder in Alexander's death.
"Everybody in my family was bawling. They were happy. ... We were all hugging and just was preparing for the next phase. The sentencing phase," Steven Alexander said.
A judge sentenced Arias to life in prison without the possibility of parole after two juries could not agree on whether to sentence her to death.
Arias told ABC News in a 2013 interview that she was "shell-shocked" by her conviction.
"I was really hoping the jury would see things for what they are. ... I didn't expect to walk away. I knew that was a possibility, a slim chance...in a parallel universe somewhere, but certainly not first-degree," she said.
Arias remains in Perryville Prison in Arizona, awaiting a decision on her appeal.
As time has passed, Steven Alexander says he's tried not to think of Arias.
"I've kind of let that part go … [Travis] should have a couple of kids," he said. "He should have a beautiful wife. He should have a beautiful home. He should have absolute happiness. And he should have that beautiful smile that was on his face all the time."