I don't think Danielle's killer is a serial killer. It doesn't have that feel to it. I would hope SD LE brought in a profiler but from the way they conducted the case, I'm sure they didn't. I have serious concerns about this investigation. P.S. My ex-husband was a cop, FWIW.
I'm not a profiler, sometimes I wish I was. It's fascinating stuff. Everything I know is what I've learned over a decade of working with people in a variety of psych and medical settings. As for citing specifics sources, Google searchers, go for it!