Home security experts warn against leaving keys in door locks

Security experts and police warn that leaving a key in a door lock from the inside overnight may not provide the protection many homeowners assume. While older standard cylinders can be blocked by an internal key, preventing entry from the outside, many modern locks feature an emergency or double-function mechanism.

With these modern cylinders, a key can be inserted and turned from the outside even if another key is already present on the inside. Homeowners can test their locks by inserting a key on the inside and attempting to turn a second key from the outside while the door is open.

Additionally, leaving a key in the lock can pose a risk if the door has glass elements. If a window or glass panel is broken, an intruder may be able to reach the key and unlock the door from the inside. Experts emphasize that the most important security measure is ensuring the door is properly locked rather than simply leaving a key in the mechanism.