The 1996 slaying of a North Texas girl that led to the nationwide Amber Alert notification system to find missing children remains unsolved.
Arlington police on Tuesday repeated their request for tips in finding the killer of 9-year-old Amber Hagerman.
Wednesday marks 20 years since Amber was abducted while riding her bicycle in Arlington.
Radio and TV stations in the Dallas-Fort Worth area joined forces to broadcast alerts to help find Amber, who was last seen alive on Jan. 13, 1996.
For several days, the entire community held out hope she would be found alive.
But then her body was discovered in a creek about three miles away, her throat had been cut.
"That was a terrible crushing blow for all of us," said Tarrant County Sheriff Dee Anderson. As the then-Arlington police spokesman, Anderson became the public face of the high-profile investigation.
The latest news from around North Texas.
Anderson said Amber's murder is a crime he can't forget.
"It's just lived with me for so very long when other things fade away," Anderson said.
And after all these years, her killer has never been caught.
"People thought all along we had some good suspects and people in mind," Anderson said. "The truth of the matter was we never got close to thinking anyone actually was the person who did it."
Amber's mother, Donna Williams, appealed for justice for her daughter Tuesday.
"As her mother, I'm not going to give up. I still have hope that he will be caught one day," said Williams. "How could you look into my little girl's tearful eyes and do what you did to her? And most of all, why did you kill my little girl? She was a 9-year-old innocent girl."
Arlington police said in the last 20 years, there have been more than 8,000 tips in the case. Investigators said they looked into every single one, with no luck.
Oak Farms Dairy has now offered a $10,000 reward for information leading to an arrest and grand jury indictment of a suspect in the case. The reward will remain in effect for one year.
"We want closure and we want justice, so if you have any information, please come forward," said Amber's brother Ricky Hagerman.
The tragedy did lead to something positive: the Amber Alert, a partnership between police and broadcasters, which alerts people to confirmed abductions.
It started in DFW and has now spread worldwide, helping save more than 700 children to date.
Anderson said for it to work, the alert system has to be used sparingly.
"If you start overusing it, we've seen around the country some places, it's the little boy who cried wolf syndrome," he said. "If you hear it all the time, nobody pays attention."
But all in all, he said, it's worked beyond the wildest expectations.
It's a source of pride for Amber's mother.
"If it were not for Amber we would not have the Amber Alert today and we would not have helped to save more than 700 kids' lives today," said Williams. "And please just don't forget Amber."
For the sheriff, it's also the only bright spot in the tragedy.
"It's at least some source of comfort that Amber will – her name and her legacy – will live on beyond any of us," Anderson said.
NBC 5's Scott Gordon and Eric King contributed to this report.