Asklemmy

Hi, I promise I have no unethical intentions with this post. And forgive the cheesy stock photo; I wasn't sure what to put there.

Avoiding specifics, a friend of mine has a physically-distant, yet emotionally-close, family member go silent for no apparent reason. This person has a history of mental illness and dissapearing from time to time, but it's been a year, and my friend is worried. The family member doesn't have much of a social media presence, and we don't know anyone who could check on them in-person. Right now I only know their name and a vague idea of their location (which is in the United States).

Here's my question (and some followup questions): How can I find any information about their existence online?

Are there any public government records I could search through?

I know there's a ton of advertising data collected by phones somewhere out there. Could that be useful in some way?