New York (CNN) -- The photographs are haunting: a toddler with huge, saucer eyes; a teenager smiling shyly; a middle-aged couple; a freckle-faced Little Leaguer.
A year ago, the Cold Case feature was launched to bring a fresh look at unsolved cases that Nancy Grace had covered. The aim was to pull these cases from their vaults, dust them off and refocus attention on them, reminding the public that police and families need help seeking justice and closure.
Through the year, the definition of a cold case evolved beyond high-profile ones such as Natalee Holloway and JonBenet Ramsey. A cold case involved anyone who vanished without a trace or was murdered, any time the police and family were left without an arrest or explanation.
Cold cases tell the stories of lives interrupted.
Although all of the nearly 50 cases featured over the past year have been special in some way and worthy of attention, a few stand out in hindsight.
Brianna Denison was the cold case that resulted in an arrest. Media coverage in September 2008 brought in the tip that led to a suspect.
Denison, 19, was visiting friends at the University of Nevada, Reno, and had crashed on the living room couch of an off-campus apartment. While she slept, someone crept into the apartment and abducted her. She was sexually assaulted and brutally strangled, and her body found weeks later in a snow-covered field a few miles away.
A month after her story was featured as a cold case, triggering a series of local stories, police in Reno, Nevada, made an arrest.
"Media coverage is absolutely essential for us," said Detective Adam Wygnanski, one of the lead investigators working the case for the Reno Police Department. "We finally got the break in the case we were looking for."
The tip came from a secret witness, who pointed police toward a suspect, James Michael Biela. According to police, the tipster saw photos of panties found near Denison's body and heard the description of the suspect's truck. She came forward, telling police she'd seen panties in a pickup belonging to a friend's boyfriend that resembled those in the photo.
Biela, 27, is in jail awaiting trial, set for February, on charges of kidnapping, rape and murder in the Denison case.
He also stands accused of raping another University of Nevada, Reno, student October 22, 2007, as she headed toward her car in a university parking garage. And he's charged with kidnapping and sexually assaulting a third student December 17.
Biela has pleaded not guilty in all three attacks. He could face the death penalty if convicted of murder in the Denison case.
But so many other cases remain unsolved, with family members living in hope of finding answers.
"There isn't a day that goes by we don't think about Chanel and pray they'll catch the people that did this to her," Lucita Petro-Nixon said of her daughter.
Petro-Nixon says she'll never forget Father's Day 2006, when her daughter left their Brooklyn, New York, home during the day to apply for a summer job at an Applebee's a few blocks away and never came back. The teen's body was found four days later, strangled and stuffed into a garbage bag left on the curb in front of a brownstone miles away.
Etan Patz's case galvanized the missing children's movement, raising awareness of child abductions. The 6-year-old vanished one morning in 1979 while walking to his school bus stop in New York's SoHo neighborhood. It was the first time he set off on the trip by himself.
Etan became the iconic boy on the milk carton, one of the first children to be featured in that 1980s campaign. Thirty years later, the case remains an open investigation, with no official suspects.
According to the U.S. Department of Justice, 797,500 children are reported missing each year, about 2,000 children a day. Many of them are recovered quickly, and some of the reports involve parental abductions. But not all.
Of the nearly 50 cases featured in the past year, the vast majority have told the stories of missing young women and children. The cases get the most attention because the victims are most at risk.
Only a small percentage of cases fall into the category of stranger abductions, said Marc Klaas, president of Klaaskids Foundation, which he formed after the 1993 kidnapping and murder of his daughter, Polly. Of those abductions, Klaas added, two-thirds are children between the ages of 12 and 17, and 80 percent of those children are females.
"It's the victims of stranger abductions that are most at risk of injury, sexual assault or death," Klaas said, explaining the urgency to cover such stories.
Even the high-profile cases can be frustrating for the people left behind. Consider the 2005 disappearance of Natalee Holloway, 18, an Alabama high school senior, in Aruba.
Authorities have acknowledged that mistakes mistakes made early in the investigation brought it to a standstill.
Each year, Natalee's father, Dave Holloway, goes to Aruba with special equipment and a search team in hopes of finding his daughter. Despite years of effort, the case remains cold.
As the cold case feature enters its second year, there are more cases to uncover, more stories to be told. Focusing attention on investigations that have gone cold is exactly what police and the families of victims need to jump-start an investigation. Denison's case serves as a reminder of that.