[This story was originally broadcast on April 24, 2010. It is dedicated to the memory of Harold Dow.]
For Rob McLeod, checking his daughter's website is a daily ritual. He said he visits "...just to see her. Just for a sec... And then there's been real emotional days that I can't possibly look at her pictures."
That's because McLeod's 19-year-old daughter, Kaysi, vanished more than six years ago, in August 2003.
Rob described his daughter as "bright and bubbly and fun. ...She was a very happy, easy to get along with, wanting to please type of kid."
"She danced and sang all the time...all around the house all the time," her mother, Lori McLeod told "48 Hours Mystery" correspondent Harold Dow.
Kaysi was the couple's only child; when she was a toddler, they doted on her.
"Kaysi was brought up in bubble wrap," Lori explained. "We protected her from everything."
But Kaysi's sheltered life didn't last long; her parents divorced when she was four and as she got older, Kaysi grew rebellious.
"She was buttin' heads with her mom and started smoking and started engaging in behavior in high school that her mom didn't approve of," Rob explained. "And she just packed her up and moved her down to her aunt's in Arizona."
Phoenix was Kaysi's new home and it was where she met best friend, Tabetha Morton.
"We were both turning 16, I believe when I met her," Tabetha recalled. "We were so close, literally, that we were practically attached at the hip. Because we worked together, we were going to school together, and we spent so much of our personal time together."
But after high school, Tabetha said Kaysi fell in with the wrong crowd.
"...there was a girl that decided to move in with her... this girl was heavy into drugs and she was bringing lots of people who were using drugs to the house quite often. Kaysi kind of fell into that," Tabetha explained. "When I noticed that something was wrong, I called her aunt. And I said, 'I think that Kaysi's in some trouble.'"
Kaysi was sent back to Colorado in late 2001.
"It didn't change our friendship," Tabetha continued. "I think it actually made it stronger, because she knew I was really looking out for her."
"She had a few months of drug use but, that's not who she was," Lori said.
As Kaysi settled back into her old surroundings, a new man, named Scott Kimball, entered her mother's life.
"He was great and he was very charming and funny and smart. Very appealing," Lori told Dow.
Now living with Scott and Lori, Kaysi seemed to be getting her life back on track with new friends and a new job. But then came a shocking disappointment; Scott found drugs in the house.
"And when I confronted Kaysi, she swore to me that they weren't hers," Lori said. "She begged me to get a drug test. And I didn't believe her."
When Lori threatened to turn her daughter in to police, Kaysi took off down the road on her bicycle. When asked what she thought happened to Kaysi, Lori replied, "I thought she took off because I didn't believe her... I worried sick about her... I drove around looking for her."
At first, Rob was angry; Kaysi had run away before.
"I was worried about her," Rob admitted, "but not to the point that I thought any foul play happened. I figured she was over... found a friend and was crashing over at their place. She'd call or eventually just show up like she had before."
Two days later, when Kaysi failed to show up for her shift at a sandwich shop, Lori became frantic.
"I went to the police and they told me that it was not my right to find her," she said. "'Kaysi was over 18, she was not a runaway. She simply left.'"
Lori said she wasn't even able to file a missing persons report. "The police won't allow that. They told me there had to be blood evidence of foul play in order to file a missing persons report."
At least Lori had the support of Scott Kimball, who had important law enforcement contacts. "He worked for the FBI," she explained. "He helped catch bad guys."
When Kaysi disappeared, Lori said she talked to Scott. He told her with his connections with the FBI, "we'll find her."
Desperate, Lori even married Scott, seeing him as the only hope to finding her daughter. And sure enough, he turned up a few leads, including evidence that Kaysi had stopped by the house very recently, when no one was home.
"He found Kaysi's necklace on her bedroom [doorknob] handle," Lori said
Even more promising, Scott found a neighbor who said he had seen Kaysi weeks after she disappeared. "And the neighbor said that Kaysi had been at the house with her boyfriend and his sister," Lori recalled.
Back in Phoenix, Tabetha Morton was also frantically looking for her friend. "I called everybody that we knew. I set up a MySpace page for her - contacted people from high school, passed out flyers."
Weeks, then months, went by. When Kaysi still hadn't been heard from for over a year, Tabetha became convinced that her friend hadn't run away and that something more serious had happened.
"It just became more and more unlike her not to get a hold of me in some way through an email or give me a call, something like that," Tabetha said.
"The most unbearable thing for me to think of my daughter is that someone took her - something precious, something important to me, and destroyed it and threw it away like it wasn't important to anybody," said Rob.
Together, Rob and Tabetha began to wonder if the key to Kaysi's disappearance might be much closer to home.
According to Tabetha, "It was just this nagging feeling that kept going through my head that there was something more than what we were finding."