In 2012, the murder rate in Chicago soared to more than 500 - that's more than New York, though Chicago is only a third the size. "48 Hours" had been in Chicago for six months investigating gun violence when Hadiya Pendleton was shot to death.
Suddenly, what had been a local story began to fuel a national debate.
"One of those we lost was a girl named Hadiya Pendleton," President Barack Obama said in his State of Union Address. "Hadiya's parents Nate and Cleo are in this chamber tonight."
Hadiya, 15, was gunned down on January 29 in a park only a mile from President Obama's Chicago home when members of a street gang apparently mistook her group of friends for a rival gang.
Until that moment, Hadiya's life had been largely untouched by Chicago violence, according to her parents, Anthony and Cleopatra. And "48 Hours" found Hadiya had no connection to gangs.
As early as the sixth grade, when she made a school video, she seemed to understand the risks for kids in her city:
Hi. My name is Hadiya ... this commercial is informational for you and your future children. ... so many children are joining gangs and it is your job to say no to gangs and yes to a great future.
"Amongst everything else she was doing, she was on the debate team ... she was a majorette, she did volleyball," Pendleton said. "Basketball... cheerleading," Cleo Cowley added.
Her parents say Hadiya was a normal, happy teenager who dreamed of being a veterinarian or a journalist.
"What did you see her growing into?" Maher asked.
"Whatever she wanted to, to be perfectly honest," Cowley said. "Best answer," Pendleton agreed.
"It's the truth, whatever she wanted and whatever it was she was going to be hugely successful at it," said Cowley.
Less than a week after Hadiya's high school marching band had returned from the president's inauguration, school had just let out on an unusually warm winter day.
"When I got a phone call from her friend and she was like screaming, 'Hadiya's been shot. Hadiya's been shot...' Cowley recalled in a whisper.
She says she literally could not make sense of it -- even after meeting her husband at the hospital.
"This can't be us," she said. "This is not our life! This is not the rest of my life!"
"I mean, only thing I could really remember is 'why they bringin' these tissues in here? Why they bringin' these tissues in here?"" said Pendleton.
"After the doctor came in and told you that she hadn't made it, what do you remember happening after that?" Maher asked.
"I died," Cowley replied. "This is my best description...you ride roller coasters? ... I think the intensity of riding the ride is hearing the click, click, click ... and then the roller coaster starts to roll ... your stomach goes, like crazy, and you reach instinctively for that bar ... it's like reaching for that bar, but never having it and never falling any further to level off."
Just days after Hadiya's murder, the Pendleton family was riding an emotional roller coaster. But they agreed to let "48 Hours" into their lives as they remembered Hadiya's life as a typical teenager.
They wanted to share their memories, in the hope that her death would mean something.
"I just think that there needs to be an awareness that, you know, there are good people out here that have promising futures that are not living to see them through because -- because something's wrong," said Cowley.
"We've got people dying ... and I'm not rolling over, I have not thrown the towel in," said Jack Riley, who thinks he knows why so many of Chicago's children are dying.
Riley, a 28-year veteran of the DEA, heads the agency's Chicago office, which controls five surrounding states.
"I wanted to retire a few years ago ... my wife's naggin' me every day... get outta the job," he said. "I can't do it!"
While Hadiya became a celebrity in death, shootings happen just about every day in Chicago.
Riley says many Chicago shootings are carried out by the area's roughly 70,000 gang members who are going to war over one thing in particular: drugs
"In your mind, there is an absolute direct connection between the murder rate in Chicago and the drug wars in the streets," Armen Keteyian noted to Riley.
"As sure as I'm sitting here telling you," he replied.
He said these days, the gangs are fighting mostly over distribution of one drug alone: heroin.
"It is right now the drug of choice for street gangs," said Riley.
A man who is risking his life to talk to "48 Hours" says the heroin is brought to Chicago by one main source: Mexico's infamous Sinaloa Cartel.
"And the worst part is they are armed," the man said. "It's practically a time bomb, and this is the reality we're living."
"How powerful is the Cartel influence in Chicago right now?" Keteyian asked.
"Very strong the influence of the Sinaloa Cartel here in Chicago and it's getting stronger," the man said.
He should know. He was once trusted by the cartel to smuggle drugs to Chicago. "I tell them if they have 50 kilos, I'll buy that...if they have 100 kilos in a week, I can sell that too," he said.
Jack Riley says the Sinaloa Cartel is run by one of the world's most dangerous men: Joaquin "Chapo" Guzman, who escaped from a Mexican prison in 2001. The Feds say Guzman is targeting Chicago specifically.
Why Chicago? "It's the same reason there's many fortune 500 companies here," Riley told Keteyian. "It is a business logistic home run."
"We're over some of the biggest interstates in the country here in addition to the trucking and obviously the rail and that's what makes this area so important to traffickers," Riley explained while flying over the city with Keteyian.
"Jack, you've got a personal history with Chapo Guzman?" Keteyian asked.
"Yeah, I hate the guy," Riley replied. "He made it clear to some of his subordinates that he would like to see my head lopped off. ... I still got my head ... get in line Chapo! C'mon let's go!"
Guzman is considered such a menace to these streets that the city's crime commission recently named him "Public Enemy Number One" -- a title they last bestowed on notorious gangster Al Capone.
"Chapo to Chicago right now is what Al Capone was in my opinion," Riley explained.
"Does that make you the modern day Eliot Ness?" Keteyian quipped.
"I've been called worse!" said Riley.
Until Guzman is brought to justice, Riley and a new multi-agency "strike force" are vowing to take down the violent Chicago street gangs that do his bidding.
"They're demanding a safer place to live, a safer place to raise their kids...and that's what it's all about today," he said.
"This is good versus evil and you're riding with good today," Riley commented to Keteyian as they headed to a pre-dawn raid.