(CBS) - It might seem like a near-miracle that 22 years after the decomposing body of a child was found inside a cooler in Manhattan
But experts tell CBS News' Crimesider that the combination of time, renewed publicity, investigative determination, technology and a reward is precisely how many cold cases heat up.
According to DNA Info, a New York local news site, over the summer police began hanging posters in the Washington Heights neighborhood where the girl's body was found in 1991, for information on "Baby Hope."
Those posters, apparently, bore fruit.
DNA Info reports that a witness came forward to tell police that she had overheard a conversation in a local laundry where a woman said she thought she might be the child's mother. Detectives reportedly tracked down the woman who provided a DNA sample which matched one taken from "Baby Hope" when her body was exhumed in 2007.
"If you put up posters in the right place, witnesses know - it happened right here," says Sheryl McCollum, the director of the Cold Case Investigative Research Institute at Atlanta's Bauder College. The Institute is a club for students to examine a new unsolved case each semester with the help of criminal justice professionals and researchers.
DNA Info reports that the mother told police her then-husband had taken the girl and their other daughter in 1991, but that she was afraid to go to police because she feared what he would do to her or the girls if he found out she had reported him.
That fear, experts say, often keeps witnesses from coming forward when a crime occurs - but can dissipate over time.
"Relationships change," says Mary Branson, co-author of "Delayed Justice: Inside Stories from America's Best Cold Case Investigators."
"People ask themselves, 'Why was I protecting this person?' And guilt increases. People who want to talk will eventually find someone to confide in."
Branson's husband and co-author, Jack, also points to the fact that, even though the crime was more than two decades old, the NYPD continued to work the "Baby Hope" case.
"I applaud their determination," he says.