For the John Does walking among us, their lives are mysteries to society and to themselves. These seemingly invisible citizens can't answer the simple questions, "What's your name?" or "Where are you from?" They are blank slates.
They aren't eligible for health insurance, can't pay rent or get a driver's license. They can't get a job or apply for unemployment benefits.
Many of them suffer from mental illnesses that render them unable to remember who they are. Scans of their fingerprints lead to no matches, indicating that they do not have criminal records. Their faces do not appear in databases for missing people.
In February, a man was brought to a Fort Worth, Texas, hospital with a cranial bleed. He did not know his name or remember any details from his life. He was admitted under the name "Bobby Jones," but only answered to "Smiley." They have guesstimated his age to be about 76. He can speak, but rarely answers questions. He is paranoid and no longer able to walk.
"I just keep thinking he was somebody's little baby once and you think about how much you love your children and what happened to his parents? Where have they gone?" wondered Kathleen Evans, the inpatient case manager for Fort Worth's JPS Health Network where Smiley was a patient.
The caretakers know that Smiley has been on the streets and in shelters in the Fort Worth area for about 20 years. He has no police record, proven by the lack of a fingerprint match. The hospital has been paying $24,000 every three months for his care, but Evans sees no other choice.
"We couldn't put him out on the streets," she said firmly. "I can't lay him out on the sidewalk. He's a human being and you have to send him to a safe place and the street would not be safe for him."
Smiley is now in a nursing home. Evans and the hospital tried every known avenue to search for his identity.
The National Missing and Unidentified Persons System (NamUs), working under the U.S. Department of Justice, has several databases, but does not currently have one that includes the living unidentified. But after being presented with a number of cases of living unidentified, they are developing a new database that they hope to launch by the end of this year.
"The traditional system is in dealing with unidentified deceased, but we know there are unidentified living," NamUs spokesman Todd Matthews told ABCNews.com. "We have to include the missing. They're missing from somewhere."
Matthews does not have an exact count on the number of cases, but NamUs is aware of "dozens" of men and women living without identities. He believes there are many more cases out there that have not been reported because hospitals and authorities don't know what to do with them.
"I think people have seen this as a homeless person and they've just fallen ill, but that's not always the case," Matthews said. "I think we're really going to have people to focus on this and see how many are out there."
"It's a real problem," he said.
Benjaman Kyle can tell you how big and bewildering the problem is. Kyle is a working, productive member of society, whose lack of identity is a daily struggle. He made up the name Benjamin Kyle just so he would have a name.
In August 2004, he was found naked, unresponsive and covered with fire ant bites behind a Burger King Dumpster in Richmond Hill, Ga. When he awoke in a hospital, he was confused.
"I had no idea who I was. I couldn't remember," Kyle told ABCNews.com. "I had no idea how I got there."
The hospital called him "BK unknown" since he was found behind a Burger King. He felt strongly that his first name was Benjaman, but could not remember his last name. When pressed by the hospital for a last name, he picked Kyle—the first name he could think of that started with a "k."
Fingerprints and searches in both national and international databases turned up no matches for Kyle. He has been fingerprinted more than five times by the FBI with no luck.
"A police officer in Georgia told me once that it means one of two things—either I've never committed a crime or I'm so good at it that I never got caught," he said with a laugh.
Despite maintaining a sense of humor, there is sadness and frustrations beneath the surface.
"I'm not in any of the databases that they can search," he said. "Basically, I don't exist. I'm a walking, talking person who is invisible to all the bureaucracy."
There are a few bits and pieces of his life that Kyle remembers.
He believes his birthday is Aug. 29, 1948, making him 64 years old. He remembers that date because it is exactly 10 years before Michael Jackson's birth date. He also thinks he was born in Indianapolis and recalls sitting in the library at the University of Colorado at some point.
Kyle has two scars on his elbow and no tattoos or piercings. He has been diagnosed with amnesia and does not know if whatever unknown events that led up to him ending up behind the Dumpster caused him to lose his memory.
John Wikstrom, 21, made a documentary about Kyle and found himself personally frustrated with how few resources there are for the living unidentified.
"People who are unidentified, there's nothing they can do. There's absolutely nothing," Wikstrom told ABCNews.com. "It's incredibly frustrating. It makes you want to appeal to the highest possible authority and figure out if someone can get him out of this mess. Someone has to be able to do something."
When making his film, Wikstrom was struck by how normal Kyle is, a typical functioning and productive member of society.
"He's witty and articulate. Talking to him, it's shocking and I think one of the more sobering facts when relating to him is because he's so relatable," he said. "He has a family somewhere, even if it's not an immediate family. This isn't just some strange, distant icicle of a man. This guy is fun, which is again, a very strange concept."
Following the documentary's release, Kyle was able to get a special Florida state identification card, but still doesn't have a birth certificate or Social Security number. He has been told that due to the presumption that he was given a Social Security number at some point, he cannot get another one.
After hearing his story, a Florida restaurant gave him a job in the kitchen and a landowner is allowing him to live in a shed on his property. The restaurant owner is paying Kyle out-of-pocket because without any information, he can't be on the official payroll.
Kyle believes he may have worked in a restaurant in the past because once he was in the kitchen, he discovered that he knew how to work the machines and fix a broken stove.
Kyle acknowledges the naysayers who may accuse him of faking his condition, but insists there would be no reason to do so.
"You'll find a lot of people who say it's all bogus, that I'm faking it for whatever reason, but one thing's for sure—I'm not getting rich out of it," Kyle said. "I'm 64. I'm trying to get on with my life as best as I can. I figure I've got 10 more years to live considering my social and economic bracket. I can't make any long terms plans other than try to get along mostly day to day."