How to tell if your locks have been tampered with

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Burglars may try a number of methods to try and gain access to your home, including picking your lock. The most obvious signs your lock has been tampered with are visible dents and scuff marks around the keyhole. While these are quick and easy to notice, here are specific signs of lock tampering that you can look for and measures you can take to help prevent unauthorised entry.

Have your locks been tampered with? Here's how to tell

Types of unauthorised entry

When you suspect lock tampering—or worse, a break in—the first thing to do is remain calm and assess the situation. What evidence do you have? For example, is anything inexplicably missing, moved, or broken? Any window, lock, or door frame deformed, smashed, or broken? If you have evidence like this, call the police to report it. If not, you might look a little closer for indications of tampering.

Before you go looking for signs of entry, however, it might help to have a basic understanding of the three main ways burglars go about getting through locks.

1. Brute force

This is the hastiest, and therefore messiest, form of attempted break-in. Often a criminal will try to bash in a lock, drill through a deadbolt, or kick down a door, leaving a trail of twisted metal and splintered wood. There are less obvious ways to force through a lock though, so you might also look for some of the following signs of unnatural wear.

Signs of brute force

  • Paint circles from lock fixture movement (like it was loosened and retightened out of place)
  • Bent deadbolts or latches
  • Warped doors/doorframes

If you notice that your key is suddenly harder to turn than usual, this could indicate pin deformation—a result of more refined methods of lock manipulation like bumping or picking.

2. Bumping

Since the early 1900s, locksmiths have used a secretive technique called "bumping" to open locks in a hurry. In 2005, a Dutch talk show revealed the process and, since then, the technique has been picked up by countless burglars worldwide.

To do this, burglars file down the teeth of a key into several points, sort of like a little saw. Next, they insert this “bump key” all the way into a compatible keyhole and withdraw it with one click. Then they strike it abruptly with a blunt object, withdraw one click again, and repeat until the lock tumblers have all caught. Finally, they turn the key and open the door.

When done correctly, this method leaves little trace. Sometimes, however, hasty amateurs can leave identifiable marks.

Signs of bumping

  • Fresh nicks around the edges of the keyhole from pounding the key a little too forcefully
  • Shiny metal edges that look like they’ve been recently hit

3. Picking

The third and most traditional method of tampering with locks is "picking." This is where a person uses small tools like a flat screwdriver to turn the lock and a pick (sometimes even a dental pick) to rake the pin tumblers. Like bumping, once the tumblers catch the lock easily turns.

This takes more time and expertise than bumping, but is gentler and therefore unlikely to leave indications like warped pins or bolts. Nevertheless, as picks and shims (i.e., screwdrivers) wiggle around inside, they can cut into the edges, leaving marks.

Signs of picking

  • Tiny scratch marks, showing fresh, shiny metal around the key hole (finer than from a key)

Prevention strategies

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Now that you know what signs to look for and how they happened, you can consider options for rectifying the problem. One of the best ways to deal with lock tampering is to change your locks to deadbolts or upgrade them to hybrid digital/mechanical bolts, which are not as dependent upon tumblers and pins.

As a bonus, electric locks help prevent you from getting locked out of your own home since they often have keypads or sync with a smartphone app.

You can also use a device that prevents the turning of a deadbolt even after it is unlocked. And in brute force situations, having a sturdy door is ideal.

It might be time to consider installing a DIY home security system. That way even after you’ve changed locks and reinforced doors, if a criminal tries to force their way back in they’ll set off alarms or get caught on tape, offering you and your family yet another layer of protection.


Get to a safe place and call 000 immediately.

A deadbolt is considered the safest type of lock.

According to Budget Direct, 4.3% of Australians experienced at least one break-in or break-in attempt in the previous 12 months.

Product prices and availability are accurate as of the date/time of publish and are subject to change. Any price and availability information displayed on the retailer’s website at the time of purchase will apply to the purchase of this product. SafeWise Australia utilises paid affiliate links.
Celeste Tholen
Written by
Celeste Tholen

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