On the evening of Oct.1, 1993, 12-year-old Polly Klaas and two friends were having a slumber party inside her home in Petaluma, a small town outside of San Francisco.

Her mother was asleep and her father wasn't at home, when a mentally unstable, career criminal crept into Polly's bedroom and took her.

The unspeakable tragedy that unfolded shocked the soul of the country and led to one of the country's most signifigant criminal justice reforms, the "Three-Strikes and You're Out" law.

In Fox Nation's "Crimes That Changed America," Fox News contributor and Fox Nation host Emily Compagno reexamines the infamous crimes that changed the face of American justice.

"The guy that murdered Polly had been sentenced to more than 200 years behind bars, during the course of his criminal history," Polly's father, Marc Klaas told Fox Nation. "But he was out. He was a 38-year-old violent recidivist offender who was back out on the street after committing his second kidnaping."

For nearly his entire life, Richard Allen Davis had been in and out of prison. On that night nearly 30 years ago, he abducted Polly at knifepoint, as her friends watched in horror, and that was the last time Polly would be seen alive.

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"She was a vibrant, energetic, outgoing little girl with a great love of theater, a great love of family," said Marc Klaas. "The night Polly was kidnapped, I was in disbelief because I wasn't there. And I heard it through a phone call and I immediately thought, I need to contact the FBI."

The search for Polly quickly became a national story, and across California hundreds of people volunteered to help find her.

A tipline was set up to receive calls 24 hours a day, seven days a week. Law enforcement and volunteers searched hundreds of acres a day.

"We generated 12,000-plus actionable leads and 60 days," recalled retired FBI agent, Eddie Freyer, who worked this case nearly three decades ago. "That's an unthinkable amount of activity."

But despite all the attention, the Klaas family and the FBI were no closer to finding Polly, as they neared the end of November.

"CRIMES THAT CHANGED AMERICA": ANTI-STALKING LAWS

Then, there was a breakthrough. A property owner in a remote part of Sonoma Country, California called the police to report finding children's clothing and a man's sweatshirt on her land.

Two months prior, that same Sonoma county woman had called police to report a suspicious person on her property.

Now, police had a name, and when they ran a criminal history check on Richard Allen Davis, they felt that they had their suspect.

Davis was arrested and facing a mountain of evidence, he confessed to murdering Polly, and he led investigators to where he left her body.

For Marc Klaas this was not an end, but a beginning. Her daughter's murder set his life on a new trajectory.

"Before my life was about my little unit, my wife and my daughter," Marc Klaas told Fox Nation. "And now my life is about more than that. It's about everybody's daughter and everybody's son and hoping that we can give them what we couldn't give our own child."

DETAILS FROM TODDLER'S DEATH SCENE MAY LEAD TO KILLER, SAYS PANEL OF INVESTIGATORS

"I wanted to give meaning to Polly's death and I wanted to create a legacy in her name," he continued. "I am not going to let my daughter's death be in vain."

Today, more than two dozen states and the federal government have a 'Three Strikes" laws. The measures vary from state to state, but the essence is the same: When an individual is sentenced for a serious crime, his or her previous convictions must be taken into consideration. If an individual is sentenced for a third crime, after two prior convictions, their sentence may be enhanced all the way up to life in prison.

To hear all of Marc Klaas' story and his efforts to pass the "Three Strikes and You're Out" law sign up for Fox Nation and watch "Crimes That Changed America."

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