Well, I'm guessing she was no more than 20 when she was "naively thrilled" that this older man, a police sergeant, found her attractive. In other words, she hadn't yet gained the caution and wisdom which should come with adulthood. Assuming Tracy knew he'd been married three times before AND that wife #3 "drowned" in the bathtub, it would be interesting to know why she hooked up with him.
Lacy Peterson...Tracy Peterson. Strange.
According to info on this thread, she was 16 or 17 when he met her at a hotel she worked at (and he was working security).
Anyway, he was still married to wifey #3 and Stacey ends up pregnant with his child at 17 years old.
My guess is he caught her stealing or doing drugs and threatened to turn her in if she didn’t have sex with him.
Then, when she turned up pregnant, she needed someone to provide, and turned to him.
So, he gets rid of wifey #3, because she was already sick of him.
That is the ‘smell’ of things that I am getting from reading all the info on this case, so far.