A couple of things: I believe that the threats were in the mailbox, because that is what the neighbor accross the street was asked, personally, by a detective, to keep watch for. The detective asked him to watch the mailbox for someone in-putting the letters. We have a volunteer postal service out here, so the postal person is one of three people who alternate during the week.
Secondly, the cameras originally were pointed at the front and back door, but after the threats started to come, I was told that they moved the front one to face the mailbox. If 2 or 3 months ago the cameras had picked up a suspect at the mailbox, they would have already worked on finding that person. However, what if the only person placing anything into the mailbox was CC or the postal worker?
Now, as Stella5 pointed out, this is a busy neighborhood. 75% of the residents of Columbia, work in St. Louis. So, of course, like anyone knows, the JB and poplar bride kinda get packed around 7 in the morning. So, anyone who has to go to work, tends to wake up around 6 and leave about 6:30, so they can get there, to one of those two bridges about quarter till or earlier, since the JB Bridge is 10 minutes from Columbia. I think someone would have noticed someone not related to the Colemans, snooping around their house or even walking close to it. Walking on the sidewalk is one thing, but walking around the backyard is another thing.
As for the window, the window has two locks on the top. You don't have to try to force an entry into a window to get a screen to rip. (we all know that). However, when someone says forced and window together, I think of broken window. How else can you open a window, from the outside, without braking it soemwhere? I may not be an expert on windows, but I do know what windows they have in that house, and they are the same as mine. No forced entry, means window was open or unlocked.