There are cold cases just about everyone knows: Tupac, JonBenet Ramsey, Natalee Holloway, Jimmy Hoffa. They're high profile mysteries that live on through continued retellings in books and on TV.

But that handful of cases is only the tip of the iceberg. The total number of cold cases is staggering. The National Institute of Justice has called it "our nation's silent mass disaster."

An estimated 40,000 cold-cases remain unsolved in the United States, usually forgotten by all but a few detectives. Half of those cold-cases are the victims of violent crimes. The others are suicides and accident victims.

"Whodunnit?" isn't the toughest question investigators face.

"Whoisit?" is generally the first and hardest question to answer.

Most of the dead are nameless, their remains stowed in the back offices of morgues and medical examiners offices, in cardboard boxes locked in evidence rooms or buried ignominiously in potter's fields.

Crowdsourcing is already common in the scientific community. Citizen scientists collect specimens for researchers or play game-like computer programs to assist in mapping the brain or fold complex proteins.

Similar methods are used to solve crimes.

On the Internet, an unlikely collection of amateur sleuths have been attracted by the thousands of languishing mysteries.

Their stories are told by Deborah Halber in Skeleton Crew, How Amateur Sleuths Are Solving America's Coldest Cases (Simon and Shuster).

These volunteer crime solvers dedicate hundreds, sometimes thousands, of hours to their creepy pastime. They probe the Internet's darkest corners in hopes of providing names for the unidentified cold-case victims. They pour over facial reconstructions, obscure databases, and newspaper archives. These digital detectives have solved hundreds of cases.

Halber, a former newspaper reporter, became obsessed with the community of online investigators by accident. She was paging through the Boston Globe in 2010 when she stumbled on an illustration of an auburn-haired beauty with a Mona Lisa smile known as the Lady of the Dunes. The picture was of a woman who had been brutally murdered on Cape Cod. The victim's hands had been cut off, her decomposing body found naked face down on a beach towel. Considered Massachusett's oldest unsolved slaying, the case had perplexed investigators since 1974.

Halper went to her computer and started Googling, only to learn that the Lady of the Dunes was far from an isolated case. She was stunned by the tens of thousands of Jane and John Does who remained nameless. spoke with Halber last month. This interview has been edited for length and clarity. How does the nation pile up 40,000 cold-cases?

Halber: Some of those cases are decades old. Very often, when the detective in charge of a case retires or moves on, the cases go into a black hole. I thought that 40,000 was a pretty big number. But since the book was published, I've heard people say "I think that figure is low." Any time someone takes another look, more and more bodies turn up.

How many amateur detectives are working on these cases?

I couldn't put an exact number on it. The biggest website,, has thousands of users, but only a small fraction of that number makes the matches. At the time I wrote the book, amateurs had solved 309 unidentified persons cases and 708 missing persons cases. It's a tricky number to pin down. Sometimes law enforcement doesn't give credit to the websleuths.

Do these internet detectives have anything in common?

They're pretty much underemployed, really smart, but their day jobs are not terribly intellectually challenging. They may not have gone to college. Some have an amazing visual sense. There's one woman who can scan the images and look at photos of missing persons and keep all the images in her head. I think essentially they all might get involved by a fluke, they don't necessarily have anyone in their families who is missing, but might have a friend or hear about the databases and they go on out of curiosity. Who doesn't love a mystery?

Are there notable websleuths in the Philadelphia region?

Carol Cielecki, she is in Allentown. She's pretty amazing. She had this bizarre series of things happen to her ex-husband and went on to solve a completely unrelated case. And then her husband's case was solved a few years after that. She's still pretty active, but has moved on to help people find birth parents. She's one of the underemployed people. She's super smart and works at an auto parts store. She's a doll -- and really funny.

Any favorite amateurs working in the field?

They're all truly amazing people. I was in Mississippi doing a book promotion with Ellen Leach (a supermarket worker who solved the "Head in the Bucket" case). She's up to eight solves! When you consider that even one is such a needle in a hay stack, it just boggles my mind how she's had to patience to stick with this pursuit.

How do self-described "boofunkles" solve a cases that law enforcement can't? And how do police feel about amateurs butting in on their turf?

There are definitely different attitudes and they vary pretty widely. Many cops call the amateurs "Doe Nuts." But on the other hand there's Det. Stuart Somershoe in Phoenix who has said he gives out assignments to websleuths, especially to Betty Brown who works in North Carolina and Shannon Vita who's in Phoenix. He's sicced them on cold cases and they've been successful.

Why do so many of these cases languish?

Once a case goes cold it's like a body in the back room: It's not making any noise. No one is jumping up and down saying, "Look at this!" They move on to the next case. The real shame, from what I've heard from law enforcement, is when younger detectives come in. They'll say they were looking through a back room and found cases they didn't know existed. Maybe someone should have put those cases somewhere where others could have seen them.

Have there been cases where a websleuth jammed up an ongoing investigation?

It's entirely possible. I spoke with two different camps of websleuths. There are those who want the cops to answer all their phone calls and reply to all their emails. Law enforcement pushes back when some of them are bizarrely persistent. But on the other hand there's another contingent that wants to be responsible. They won't forward just any proposed match to police. They'll do research to find out if there are biometrics to support the match and consider that as they meet in committees. They won't pass along anything that doesn't look legitimate.

Have you tried to solve a case yourself?

I was intrigued after coming across the Lady of the Dunes whose remains were found near Provincetown. That was how I got into this whole thing to begin with. I did ask [amateur investigator] Bobby Lingoes to walk me through it, asking him if I were to solve it, how would I do it. That's when I realized I would be a really lousy websleuth. It's such time sucking, detail oriented work. It really is difficult trying to keep it all in your head. And it's so easy to wander off the path.

What are some of the largest websleuthing organizations and how did they come to be?

The Doe Network is probably the oldest and it's dedicated to the idea of matching up unidentified human remains with missing people. NaMus (The National Missing and Unidentified Persons System) is another that came along relative recently. Namus has more bells and whistles and can try to match DNA and other possible evidence. The Doe Network doesn't upload dental records or anything like that. Some of the early websites were developed by coroners. medical examiners and state police. They used to have their own websites that copied the Doe Network idea, but they have since been rolled over into Namus.

What is your next project?

Having done this I've heard from so many people who have heart wrenching stories. I really want to bring some of the additional ones to life as magazine pieces. It's just really agonizing to hear some of these families, especially of the missing. They don't hear anything from law enforcement after the first few weeks. Then years go by and you can't imagine what it's like to not know.

This story has been modified to include the correct spelling of Carol Cieleck.