Hmmm...this is interesting. Has a police report been filed? It's easy enough to do and at least gives a strong Heads Up to SOMEONE at the police station(s).
https://www.fairfaxcounty.gov/police/crs/IncidentInfo.asp
Note that "Suspicious event" or "Suspicious person" is reportable - and this certainly qualifies as a suspicious event/person.
[that link I just gave is actually a little further "into" the reporting process - just before that is an agreement to not lie, essentially]