I only wonder why this hasn't happened sooner. Amazon has updated its Echo devices to listen for intruders when no one is home.

Alexa Guard is enabled by the homeowner by saying: "Alexa, I'm leaving".

At that point, Alexa turns on the microphone, actually it's always on, but instead of the wake word, it's listening for the sound of someone breaking into your home.

If it picks up the sound of a door banging open, people inside or shattering glass, it will send a notification to your phone so you can call police. If you have a home security camera in the house, you could, of course, open its app and see for yourself what's going on. And if you are an ADT customer or have a Ring doorbell installed, Alexa will call police for you.

Amazon also said Alexa will be listening for alarms such as a smoke or carbon monoxide detectors and will notify you if those are set off.

Why this hasn't been an Echo thing before now, I'm not quite sure. The capability has existed from the beginning. Alexa can find your phone, play Jeopardy, give you the weather forecast for crying outloud.

There are third-party skills where Alexa can fight crime.

"Guard Dog" is an Alexa skill that makes the sound of dogs barking and growling just by asking Alexa to "open Guard Dog".

"Burglar Detector" plays sounds that make it appear someone is in the house. Enable this skill and it will play sounds of pots and pans banging together for the Echo in the kitchen, and the sound of printers, computers and music for an Echo in the office.

Alexa Guard is rolling out to all Echo devices now. You can look for it by saying: "Alexa I'm leaving". If the feature has not been installed on your devices she will only say: "Okay, bye".