Mikelle Biggs, 11, was alone for less than two minutes when she vanished.
It was dusk on Jan. 2, 1999, when Mikelle and her younger sister Kimber -- lured outside by the sound of an ice cream truck -- waited patiently at a Mesa, Ariz., street corner to buy treats. Kimber got cold and walked home, just four houses away, to get her jacket. When she returned, Mikelle was gone.
"I looked down to the end of the road and I didn't see her," said Kimber. Mikelle's bicycle was found with the wheels still spinning and two quarters for ice cream discarded on the ground.
If you have information that might help solve the mystery of what happened to Mikelle Biggs, please contact the Arizona Police Department on their website, http://mesaaz.gov/police/, or by phone (480) 644-2211.
Mikelle's mother, Tracy Biggs, was terrified. After a fast check for Mikelle at a neighbor's, she called 911.
"After I called the police, it kind of hit me then ... the panic," she told ABC News correspondent Elizabeth Vargas.
"You go cold inside," said Mikelle's father, Darien Biggs. "That first hour was it was really like walking in a dream."
Police responded immediately, and within 30 minutes a helicopter was in the air with a loudspeaker announcing that a child was missing. The Biggs' community quickly became the scene of a desperate search, spearheaded by worried and supportive friends. Neighbor Pamela Morgan remembers the evening vividly.
"From the moment that Mikelle disappeared, everybody just came together ... handing out fliers to everyone and going house to house, street to street," she said.
"All of a sudden, our little safe neighborhood wasn't safe anymore," recalled her husband, David Morgan.
Mesa Police Det. Jerry Gissel was assigned to the case the following morning. He asked Kimber to re-enact her movements from the night before. They determined Mikelle had been alone on the street corner for approximately 90 seconds.
"She was running from somebody, based on the evidence that we do have," said Gissel. "It wasn't somebody that she knew or wanted to be with. She dropped the bike, she was running toward home, she dropped quarters, and it was swift. And somebody grabbed her and, I believe, abducted her in a car and drove away with her."
Mikelle lived in a family-friendly and busy neighborhood, but police soon discovered there were no witnesses.
"Sheer chance," said Darien Biggs. "If the person that took her had been off by 30 seconds either way," it's likely someone would have seen it.
Since Mikelle disappeared while waiting for an ice cream truck, police investigated every ice cream vendor who could have been in the area that evening. But there were none. Police began following up on thousands of tips.
"We received an enormous amount of leads. ... Going through all that information was a huge task," said Det. Domenick Kaufman, who joined Gissel on the case. "We've been everywhere, at residences in Mesa, pig farms ... dump sites, the desert ... the mountains. ... You name it."
Police traversed all of Arizona and beyond in what would become the largest investigation in the state's history.
One of the most promising leads came from an e-mail message sent to Darien Biggs, in which the sender indicated he was holding Mikelle for ransom. Police tracked that e-mail down to a location in Phoenix and organized a SWAT team.