First time poster here.
I realize that I'm in the minority, but I actually think that this was his first murder. It's clear that he had a general plan as far as how to dispose of a body should the need ever occur, but the detail necessary to pull it off and walk free simply wasn't there. Leaving the tool he used to dismembered her, dumping parts of the body in recycling bins rather than trash bins, and (in my mind the biggest giveaway) selecting a victim whose family and friends were aware of his presence in her life. To me, what we know so far does not suggest a transient serial killer.
If I accept the premise that he has killed before, I still don't think that murdering Ingrid was ever the plan. He seems to have managed to maintain friendships and relationships in the past, even if only as a front. I wonder if he meant for her to be one of those relationships, something happened that angered him, he killed her, and he couldn't quite manage a cover up, or even to settle on the best course of action, because it wasn't in the plan and wasn't part of his usual MO. So, he frantically tried to weave a decent cover story/circumstance that would suggest possible responsibility of anyone rather than him (since he knew that her friends and family knew where she was and knew who he was), decided that body parts in different places would make evidence harder to collect, showed up at his ex's because he figured that running would leave no doubt of his guilt in anyone's mind, and still couldn't come up with a better explanation from the night before than that he was drunk and didn't remember.
All just my opinion, of course.
