(HealthDay) -- The Oertel family lives in a red-brick, two-story house tucked in a tree-lined, suburban Maryland cul-de-sac. There's no fence, just a small alarm company sign on the lawn that gives no clue to the system's real purpose.
The array of bolts high on the front door, the upgraded locks on the patio and garage doors and the "burglar" alarm are meant less to keep out intruders than to prevent 15-year-old Luke Oertel from silently leaving.
Luke has a moderate form of autism, a developmental disorder that affects a child's social interactions, language and behavior. He is among those with autism who wander without a typical child's sense of fear or danger.
In June, Luke outsmarted a system of combination locks and wandered five miles away, through the early-morning rush hour, taking a pedestrian underpass beneath a heavily traveled road off the Capital Beltway.
Two hours later the police brought him home, still in his green pajamas, handcuffed.
It was "sheer terror," said Luke's mother, Gwynne, of the moment when she and her husband realized Luke was missing. To protect their privacy, the family asked that their real names not be used.
Last year, "autism wandering" became an official diagnosis in the United States with its own medical code. Some of those afflicted enter strangers' houses. Others end up in traffic or on train tracks. Many find their way to nearby pools or ponds.
An aura of constant vigilance exists between Gwynne and Tess Oertel, Luke's older sister. "Are you with him?" Gwynne calls. "Is he up there?" When he's not in the same room, his mother scans doorways and listens for a wrong sound. It's unconscious by now.
In the kitchen, a heavy, padlocked chain around the refrigerator keeps Luke from tearing into the food. The pantry is also secured.
Today, Luke, a well-built teen with dark red hair and a couple of pimples, is wearing a Washington Capitals hockey T-shirt and thick brown pants. Hidden beneath his sock is an ankle bracelet. It's bulky in the middle where the battery sits, and it's water-resistant. He can't get it off, his mother said, and now he's used to it. There are no scissors in the house. The bracelet allows radio tracking of Luke's whereabouts, within a range of one to two miles.
About one in 110 children is estimated to have an autism disorder. Some are hypersensitive to sounds, smells and touch, and an "itchy" shirt or a vacuum's drone can be highly disturbing.
It is thought children have individual "triggers" that lead them to wander -- either to get away from something that bothers them or to seek out their particular fascination, such as water. As a result, drowning and exposure to the elements are top causes of death for those with an autism spectrum disorder.
From the Kennedy Krieger Institute in Baltimore, Dr. Paul Law led a study that provided the first national figures on wandering. The survey, conducted by the Interactive Autism Network, comprised more than 800 parents of children with autism.
Nearly half of these children between the ages of 4 and 10 had wandered at least once. However, because this was a self-selected group of parents -- not a random sample -- the results might not reflect the experience of all families.
Law said that no matter how vigilant a parent is, some children bolt.
When Samantha Gardner's 5-year-old son wandered off to a Brighton, Mich., ice cream store last summer, she was hyperventilating in the recorded 911 call.
Minutes earlier, a store employee had also called 911, reporting a "child that just popped out of nowhere; he seems to be potentially autistic and was running into the road." The staff kept him safe until Gardner arrived.
"With my son, 'asks permission' doesn't exist," Gardner said. "He doesn't talk. He can't ask to go to Dairy Queen."
When a child wanders, it can take just a few minutes for the worst to happen.
Beth Martin of Lawton, Okla., sometimes used a tether to keep her daughter Savannah, who had autism, safe outdoors. But her constant vigilance wasn't enough, and Savannah, 7, drowned in February 2011.
Savannah had a history of wandering. "I tried hard to do all the precautions I could," her mother said. "I knew she was a child who could go. I was trying to stay one step ahead."
On that day, in a matter of moments, Savannah had slipped away to a nearby pond and although her older brother and a neighbor tried to save her, it was too late.
Months later, Martin recalled that painful time. "My husband was deployed and I was uncomfortable with the ponds near our house," she said. "I was looking for a safer place to live."
The day before the accident, Martin had the door alarmed because Savannah was getting up at night. "But I was comfortable during the day that she knew not to cross boundaries. It was simple as that. Kids with autism have routines. I was making noodles and she always waited for noodles. I went to the bathroom and when I got out, she was gone."
Martin said she shared her story to help other parents.
For the Oertels, a factor in their decision to move to Montgomery County, Md., is that it's part of Project Lifesaver. The program provides known wanderers with radio-tracking devices and coordinates with local emergency agencies. Officer Laurie Reyes heads the Montgomery County program, where officers respond to calls about missing children with autism about every other week.
Police quickly arrived at the Oertels' home, using police dogs to search the house. Gwynne requested a helicopter, which can detect signals for three to five miles, but the police said it was too early in the search to employ one.
Luke might not have been saved without the intervention of two Good Samaritans.
A woman in a car spotted Luke on the road in his pajamas, and followed him to a hotel parking lot. She enlisted the hotel security director's help, and they trailed Luke to the Metro station, followed him by foot onto the platform and blocked him from entering a Washington, D.C.-bound train. He recited his phone number for the strangers, and they contacted his mom.
Police still had to get Luke safely into the car. Reyes recounted rescue steps: "We'll have to stop traffic. Mom has to grab his favorite food. We tell her, 'We may have to put him in handcuffs, for his safety.' Mom got it."
Oertel said she was "fine" with the handcuffs -- although she didn't want to see them applied and asked the officers not to use a Taser on her son. By 8 a.m., he was home.
Despite the blistered feet from his escape, Luke has said he wants to do it again.
Autism advocacy groups want wandering incidents to trigger Amber Alerts, but because that system is meant only for abducted children, wanderers don't qualify. A grassroots movement is afoot to implement "Mason Alerts," named in honor of Mason Allen Medlam, who drowned after wandering.
Luke attends a local high school, where he's in a six-year program to learn functional life skills. He continues to plays hockey on a special team.
"My first concern is his safety, keeping him safe," Gwynne said. "That's the number one priority. My second is his happiness. So, we're trying to expose him to all different hobbies to see what he likes. If you don't expose him to it, you'll never know."
Explore further: Mothers of kids with autism earn less, study shows
AWAARE (Autism Wandering Awareness Alerts Response Education) offers a wealth of resources on wandering.