Thats not fully accurate.
There are 2 ways to prove stalking:
1. The victims knew they were being stalked and that put them in fear of their life.
OR
2. The victims don’t have to know they are being stalked -
however, the DEFENDANTS actions caused or attempted to caused them substantial emotional distress.
That 2nd option doesn’t require victims to know or feel like they are in danger.
Simply following (or surveilling) someone with the intention of hurting them, in a way that would make any reasonable person anyone suffer substantial severe emotional distress - is enough to satisfy stalking.