re security issues.
one of the things that some folks are doing to deal with burglars is set up these motion activated web cams. I think they come from the technology that biologists used to track and watch cougars and other animals in the wild. They set up these cams, and then review the footage later on.
But folks can buy them put them around the property and they will document someone illegally coming on your property.
Cost ranges from pretty low to, you know, much, much higher.
I believe most jurisdictions only allow video, without sound. Video with sound, I believe, violates wiretapping laws.
As far as unknowns and mysteries go...the statistical possibilities are strongly in favor of very simple, innocuous causes.
A cell phone on a property? Oh, could be someone dropped a cell phone several miles away and a dog or raccoon got it and transported it. Or other simple, non-sinister causes.
As far as security issues are concerned, generally...there are a lot of simple things that can help secure a property.
Lots of light at night, for one.
If a burglar is deciding which house to engage, he is certainly not going to choose the most well lit ones. Then, into a good strong security door, some folks get these metal grates that cover the first floor windows (from the inside or out)...and that is like putting bars on your windows.
You can actually buy tape recordings of a large dog barking. That will dissuade a lot of burglars.
Here's a general info link:
Crime Prevention and Safety Tips
From the New York City Police Department
https://www1.nyc.gov/site/nypd/services/law-enforcement/crime-prevention-and-safety-tips.page