Amber Hagerman was 9-years-old when she was kidnapped and murdered.

Most people have experienced the feeling of hearing an alarm sound, and looked down at their mobile device to see an Amber Alert. But most don’t know the harrowing story behind what is now an all-too familiar call for help.

Detective Ben Lopez of the Arlington Texas Police Department still remembers the afternoon of January 13, 1996. He was a patrol officer at the time Amber Hagerman, just 9-years-old, was snatched off her bicycle in the parking lot of a local grocery store.

The only description was a blue truck that was seen leaving the scene. Lopez was quickly pulled onto a special task force to find Amber.

“For those first few days, we spent all of our extra time looking,” Detective Lopez told Dateline NBC. “It was like if you weren’t on another call, you were actively looking for her. We were looking everywhere in the city.”

Despite national attention and widespread media coverage, a dog walker came across the little girl’s body five days later floating in a creek just miles from the grocery. Her throat had been slit.

Last Wednesday marked 20 years since Amber was kidnapped and murdered, but whoever stole Amber away has not been identified. Law enforcement and family members gathered in Texas the day before the anniversary for a tearful press conference to once again ask for some type of answers.

Decades of Dissonance

Thousands of tips have poured in over the years, most in the weeks and months after Amber vanished. A handful are still phoned in every month. Despite all this, officials say they are no closer to solving Amber’s case.

“It’s been extremely frustrating for it to go on this long and not have it solved,” said Detective Lopez. “We have other cold cases and they’re all frustrating, we want to solve them all, but 20 years is a long time. It’s frustrating not to be able to give the mom and the family an answer.”

Amber’s younger brother, Ricky Hagerman, who was riding his bike alongside Amber that day, joined in the plea for answers at the press conference.

“I didn’t quite understand what was going on,” Ricky Hagerman, now 25, said at the Tuesday press conference. “We want closure and we want justice, so if you have any information, please come forward.”

Even today, Detective Lopez still pursues each lead as if it were the first. “We continue working the case. We still investigate every one of those leads like it might be the right one.”

Out of the darkness

Families across the country mourned for the Hagerman family, including Diane Simone, a massage therapist and mother from Dallas. She called a local radio station the day Amber’s body was found, asking if local broadcasters could team up with law enforcement to somehow get information out immediately following a child abduction.

It was a call that would change hundreds of lives in the years to come.

Later that year, Dallas Fort-Worth Broadcaster’s established a coordinated system with local law enforcement whereby they could warn the public when a child was kidnapped and in danger. Over the years, the system has gone nationwide.

The alert bears little Amber’s name, but stands for America's Missing: Broadcast Emergency Response. As of December 2015, the system has helped bring 794 children home safely. “If it wasn’t for Amber, we would not have the Amber Alert today,” Donna Williams, Amber’s mother, said at the press conference this week.

In December 2015, Facebook announced a partnership with the National Center for Missing and Exploited Children so that Amber Alerts would show up on users' news feeds and notifications would be sent to those in the surrounding areas.

Though the pain of losing Amber was raw on the Hagermans' faces this week, the alert ensures her name will never be forgotten.

“It doesn’t bring Amber back for Donna,” said Detective Lopez. “But at least there is something that she can look at and recognize that her daughter has at least helped so many other kids.”

If you have any information about the Amber Hagerman case, please call the Arlington Police Department at (817) 274-4444.