This happened a couple months ago: An acquaintance (we’ll call him Egbert) who was estranged from his wife (we’ll call her Namaa) became drunkenly angry about her refusal to communicate with him, and began talking at length about how he was going to kill her. Not just incoherent ranting, but specific plans: waiting for her outside of her work or outside where she was staying, etc. (He said, “She thinks I don’t know where she’s staying, but I do.”) He seemed serious enough that I thought I should get ahold of Namaa and warn her.

I didn’t know her last name, and I couldn’t immediately get it from Egbert’s social media pages, as he didn’t make them public and I wasn’t connected to him on any social networks. However, when I Googled his full name and her first name, the search results turned up his social-networking pages, and the two-line snippets on the search results page showed pieces of his connections lists (from before he had set his profiles to be more private?) that included Namaa’s full name.

First Lesson: Locking down your social-media settings isn’t a guarantee against leaks. If the last time a search engine crawled your social-media pages was before you locked down those settings, it may have stored the previously public-viewable version, and will show snippets from them.

I then found Namaa’s social media profiles, sent her connection requests with warnings, and left a message on her work voicemail — having identified her employer from her (public) LinkedIn profile. When Namaa accepted my requests and returned the phone call, she was surprised and very concerned to learn that Egbert knew which facility she worked at and where she was staying.

I followed up to suggest that Namaa check her phone’s privacy settings and turn off Location Services on all of the apps except Maps, using the linked instructions at our Step Up Your Settings page, and also check her location-privacy settings on the social-networking websites themselves (which may cover different pieces than the app settings). She responded to thank me and say she had followed my advice.

Second Lesson: If you have any reason to worry about someone trying to find you — especially if that person is connected to you on social media — check your location settings on all your devices AND on each of the social-media sites you use.

Third Lesson: Share what you know about online privacy with others — even the ones who are specifically trying to hide may know less about it than you’d think!

(I also advised Namaa that if she wanted to try to disconnect from Egbert on social media, she should be more careful about accepting connection requests from strangers, as he could always create a fake identity!)