Do you think the co-worker was somehow involved?
SBM
No I don't think any co-worker, with the possible exception of NK, was involved in the crime, but maybe, yes, in omission of essential evidence. It's just that there are so many loose ends, and possibly it's my own fault for not remembering all of the discovery and content of the interviews.
IIRC NK said that CW sent her a text, or texts, saying that the family was gone. She got this/these at 3:45 when she got home, and since Jim was there at her house she didn't pay any real attention to CW's texts until later. Well, I think she actually did know about CW leaving work early, and that his family was missing. And I think she knew about this before she left work.
IMO all his immediate field co-workers, the guys, the ones interviewed, knew about the affair. Why? Because it doesn't make sense that one of the co-workers would notice that CW was staring at NK every morning as she walked in to the meeting room, to the refer and back out, and that none of the others would notice that, and that they wouldn't joke, or wink, about it. And that he saw CW/NK very close together in the office, and that no one else noticed. Well, everyone notices things like that in an office where there is one sexy looking woman and a bunch of 30-40ish outdoorsy workers.
So, I think the guy who went back Tuesday morning already did know about the affair, knew about the family missing, and this contributed to his going back again. But there is a piece missing there, IMO, the "why?". Yes, he noticed CW wasn't wearing the right shoes, his clothes were old ones, one pant leg was in, one out, he was parked in the wrong place, was distracted, etc. But "what else"?
I think guys cover for each other re extramarital affairs, and that a whole bunch of guilt was building up in this guy, sensing a more ominous scenario than he realized the day before.
So, we have some key ppl knowing, IMO, about the affair, about CW leaving early on Monday, about the family going missing. There just isn't any way that NK, being back in the office, would not have picked up on the fact that he left early. She said she was thinking he had just arrived home from work at the normal time.
I keep coming back to the 111 minute phone call before he murdered his family. I'm open to entertaining that there was a big blowout ensuing, started at the sports bar the night before, and reaching the apex on Sunday night, we've all mentioned this. But, was she so angry (at his vacillating on the apartment, no apparent movement towards divorce, etc), that she went over to his house to have it out with him. Knowing that there was no way SW could get back until 2. am. "And then what happened"?
I am on the conservative end of the spectrum of conspiracy advocates. So I have to leave it like this IMO 1) the coworker who returned to the site knew something hinky was going on, and that NK was in there in one way or another which made all his suspicions based on something a lot worse than CW having baggy clothes and old shoes on. And 2) NK knew, IMO, right at the time CW left work that something was up with the family (if not way before), and that whole story about not paying attention to CW texts until later after her friend had left....bogus.