No,you misunderstand. How did this "anonymous donor" know BEFORE SP was found and told what happened? How did heknow in that first couple of days she was kidnapped and being held by someone?
It's extremely rare that a suburban mom goes missing and it turns out like this case did. There are other, more common reasons suburban wives/mothers go missing. Either they took off (marital problems, nervous breakdown/mental problems, affairs, or they are raped and killed and their bodies buried somewhere).
In my 20s, my younger sister went missing. My family and I didn't know she was missing until day 3, when her idiot of a husband finally called us (she lives 2000 miles away from us and we spoke once a week: this was in the days before iphones, texting and social media, so we wouldn't have known yet something was wrong). Our first thought NEVER would have been that she was kidnapped and being held for ransom, or for sex trafficking, or for torture, or to be held as a sex slave for a newly released prisoner. No. Sickening as it is to remember, our FEAR was that she'd met a fate like so many other young women meet - that she was followed home, raped, and killed). Our HOPE at that point was that it was something like she was angry at her husband and took off to punish him, or even that she was off with another guy. The reality turned out to be anger at her husband (we found out he'd hit her - for the first AND last time, thankfully - and she had taken off).
Had a guy called me and said he was a hostage negotiator and told me that there was an anonymous donor who thinks she was taken and being held, and he was going to put up money to get her back, I'd have been suspicious as all hell, slammed down the phone, and reported him to the police.