Deputies found a 24-year-old man dead inside the home and a 15-year-old boy being detained by the resident, Christianson said. In addition to the male resident who shot the intruder, a woman and a child live in the home, he said.
The woman answered the door at the home Thursday afternoon. She said she had her 7-year-old daughter hid in a closet when the suspects broke in, but she declined to comment further about what transpired.

Source: Empire resident fatally shoots home invasion suspect | The Modesto Bee

Not saying that a dedicated armed robber won’t make his/her way inside a house, but why make it easier for them by opening the door?

We live in an era where safety items are affordable and available with one click of our computers.  Besides the well-mentioned deep bolts and other mechanical devices, you should invest in cameras to see who is outside knocking on your door.

You can start on the inexpensive side and for just under $50 you can get a basic peephole camera that comes with a small monitor for the inside of the door. It is battery operated and comes with great features like low light and automatic picture-taking every time anybody rings the bell. Some models with fewer features will cost less, so it is up to your budget

Then we have basically the same system as above, but instead of screen, it goes via WiFi to your smart phone or other device. The obvious advantage is that you can monitor from anywhere in the house or even away from home.  The disadvantages are that you depend on a dependable internet connection and reliable electrical service.

The most expensive of the wireless systems would be the ones that generate their own signal to transmit the images from the cameras to the stand-alone receiver. Depending on the number of cameras and other goodies, we are talking about at least a couple of hundred bucks for the most basic system and old school with hard drive recording. Modern ones are slimmer and tabletbased, but they will be more expensive. 

Security is all about layers: the more you can place between you and a criminal, the better. It does not make sense to willfully peel a layer so important as the front door because we cannot see who is calling and decided it is worth the risk to open it.

“I don’t think it had ever occurred to me that man’s supremacy is not primarily due to his brain, as most of the books would have one think. It is due to the brain’s capacity to make use of the information conveyed to it by a narrow band of visible light rays. His civilization, all that he had achieved or might achieve, hung upon his ability to perceive that range of vibrations from red to violet. Without that, he was lost.”
― John Wyndham, The Day of the Triffids

PS: Yes, I know there are classic optical peepholes, but even a Luddite like me can appreciate the advances in electronics, that is why I also did not cover wired surveillance camera systems. The idea of having to lay cable all over the house and waste a weekend doing it will not be appreciated by most people. Most of the wireless systems are Plug and Play.