If someone dies unexpectedly, how do you find out?
Aside from being contacted by a family member or maybe some sort of contact information being left in a will, how do you discover if someone you know has died?
The authorities will try to notify someone in the immediate family (often the spouse). After that, if you are in their estate, the trustee should make a good faith effort to contact you. Beyond that, it's normally just friends and family contacting each other.
Back in the days when printed newspapers were common, some folks would check the obituaries regularly.
You could create a Google alert. If the stupid thing actually works, you should get an email when their obituary gets posted somewhere.
The authorities often go with address if they don't have any other clues. When my mom died, she lived with her sister, who hates me and my sister... We found out by chance because my mom's boss reached out to offer condolences, and then we had to call the coroner to let them know she had living kids. Her sister hadn't revealed our existence.