There is no more more important question about living in a place than "Is it safe?" If you don't feel safe, nothing else really matters.
Also, safety is a personal, "feeling" issue; statistics and other people's opinions are not as important than how one feels. As founder of Best Places in the World to Retire, I've interviewed hundreds of people living in the Ajijic / Lake Chapala area, and none of them are more worried about violent crime than they would be in their home country; some quite less so. I have seen and interviewed 70- and 80-year-old single frail-looking women, who move around Ajijic with no feeling of being unsafe, and without any incidents whatsoever. Many have lived here decades.
That doesn't mean that you can do stupid things and have no consequences. Just like anyplace, it is not wise to flash a lot of cash, be extremely drunk by yourself and walking through dark allies. Common sense applies here just like any other place.
I must admit, though, that when I first came to Mexico, with my eyes more attuned to how things looked when they were dangerous in the US or Canada, it looked very unsafe. I saw lots of high fences, barbed wire, security guards with guns, etc. To me, all this shouted: Unsafe area! Beware!!
However, all these items are not generally to deter violent crime; they are to deter theft, which is higher than I am used to in the US. If you don't have these measures, there is a higher chance that you will have something stolen than if you lived in a safe suburb of the US or Canada.
Also, I should point out that the Mexicans in Mexico (certainly in Ajijic) are not at all like many of the Mexicans you may meet in the US. Mexicans in Mexico are much more traditional and much less aggressive, to the point of being perhaps overly non-confrontational and even a bit passive. They tend to be very gentle people.
So, to summarize and personalize, I don't worry at all about violent crime, but we do take measures to guard against theft. If you do the same, you should feel extremely safe here. We do.
The picture is of a typical person you might meet in Ajijic. This woman did some sewing for me. Here's the video.
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