SEATTLE -- Burglars have an easy way to open your locks without a pick. It's called lock bumping.

Most homeowners have never heard of it, and Seattle police detective Donald Henderson had never seen the technique until we showed him.

"It's so easy, I'm just totally surprised how easy this is," said Henderson, who has worked nearly 30 years as a cop and works property crimes with an emphasis on home burglaries.

Locksmith Thomas Lambert says 90 percent of locks on American homes are junk. He calls them an easy target for lock bumpers.

Thieves can cut a blank house key, then use the key to bump or pound on a lock. Practiced lock bumpers can open a lock in about one second.

"I think it's important to talk about it because the bad guys know about it and if they don't know about it, they're going to learn about it," Lambert said.

Amy Braun's family learned about it the hard way. They got lock-bumped in April, on Friday the 13th.

Everyone in the house, including baby Annabelle were asleep. "It was very unsettling and scary at the time," says Braun, "I remembered locking the door, but I thought we must have left the slider unlocked."

The Braun's is another case where police had no idea the family was lock-bumped until we pointed it out.

"It was very quick, it just sprung right open," says Braun, as she watched detective Henderson work her dead bolt.

He bumped Amy's lock and she recognized the distinctive sound of lock bumping. "'Ping,' hear that?" asks Henderson.

It was 12:30 in the morning when Amy heard something, but convinced herself it was the house creaking. The next morning her laptop, breast pump and other valuables were gone. The door was wide open.

"I'm so glad I didn't get up when I heard the noise," she said.

Amy is resting a lot easier now. She's getting a new lock that can't be lock bumped. And even better, Detective Henderson arrested the bad guy.

Henderson thinks the suspect is responsible for six recent break-ins, each time allegedly bumping his way inside.

"Everyone I talked to has heard a noise," said Henderson. And, in each instance, homeowners assumed they forgot to lock up.

And why wouldn't they? With lock bumping there's no sign of forced entry, and homeowners naturally blame themselves.

At Bulger Safe and Lock in Lake City, Tom Lambert has heard the same blame game. But one customer knew something wasn't right.

"We had a man about a year ago -- his medicine was disappearing," said Lambert. Even after double checking his locks, his pills kept vanishing. Lambert figured out his customer was being lock bumped.

He changed the man's locks and the problem stopped.

"It's amazing how many people come into this shop that are absolutely terrified cause they've been broken in to," he said.

Local locksmiths say the same thing: lock bumping is so easy even a child can do it. So we went went to my house to see if I can lock bump my very own front door.

A lock-bumping attempt sounds like a mental 'ping.'

It took me about 20 minutes, but I broke into my own house. I probably tried 200 times to bump the lock and, at one point, I thought I had a good lock that would be safe from lock-bumpers.

Then, it happened. I kept working at it and, sure enough, with a blank key that matches my lock, I got past the dead bolt.

Henderson has this message for thieves who might want to try the lock-bumping method: "Keep looking over your shoulder, because I'm gonna be right behind you one day, and I got the handcuffs and I will click 'em on," he said.

We contacted more than a dozen local locksmiths and they recommend three locks, which they say are bump-proof. Most of the locksmiths prefer Medeco locks, but they are the most expensive.

Also highly recommended where two kinds of Schlage Locks: the Primus and the Everest. The bump-proof locks range from $150 to $250.

Detective Henderson says he plans to use our our video of him bumping a lock to help teach other officers about this threat to homeowners.

"The bad guys are always two steps ahead of us, we're always trying to catch up, but we get 'em though," he said.

Locksmiths say pin-tumbler locks are one most common types of residential locks and are not bump proof.

Safety experts say some other ways to protect your home include: dead bolts that lock from the inside, leaving lights on to keep burglars away, cutting back hedges and bushes that block your front door and considering an alarm system.