He was first confronted by a young man who worked in the store who came out and asked what he was doing in the trash. The employee went back inside after BM gave some mumbled response. I think BM was startled by that employee, because he thought the store was closed. He realized he needed to come up with something plausible so he then knocked on the door and gave them the issuing wife story and wrote the note.
Ah - it would be good if the many news articles about that night included that fact - young man's view seems to be lost in the mists of time.
But that's a good sign - it's possible that the young man could be called to the witness stand.
So if Barry first came, thinking the store was closed (not a very close observer of things, apparently - as two people were moving around inside, lights were still on, and surely at least one employee car still parked in back)...he goes through the trash. Is caught.
Thinks about it in his own Barry-way and comes up with, "I am here digging through the trash in order to tell them about my missing wife - I needed something to write on."
But he has no pen, so the lady gives him a pen and he writes what's uppermost on his mind (the items he used to stage the crime). At least. that's how I'm thinking about it now.
What a dope. True fact: research shows that people who are
less competent at something are more likely to rate themselves higher on that task than "others." I'm sure it's because they need to think someone is worse than they are - but people who are truly good at the task usually say they frequently meet people who are higher on that task than they are.
Barry is no criminal mastermind and although I think he thought about killing Suzanne (and wanted to, maybe not 24/7 but often), he did not work out his alibi plan well at all. He focused all his energy on planning and carrying out the crime/body disposal as murderers so often, understandably, do.
But his alibi circle (going to a market he already knew, calling on the few people who he knew he could get to show up for a non-job, perhaps telling family members he was on training, etc) is very poor. I give him a D+. He didn't fail altogether - he did something that threw LE off (they've probably searched every place he stopped over a several day period and come up with nothing or not much). He also managed to convince key players in his own family of his alibi long enough to carry out his financial machinations.
And I think he spent an inordinate amount of time playing shell games with money and moving "assets" around and selling shell companies and paying people under the table while somehow getting approved to work for the State of CO, etc., etc.