Hello,
I am a newbie here, but have been sleuthing around the internet since 1993! Just didn't know about this site - some sleuth huh?
When you think about the small towns in the Midwest, well, even Denver, you must think "Grid" every town is laid out on a grid. Now, look at the angle they photographed the house from, it's on a corner lot. There are two streets to access this house from. Not likely the police would pull up to the house from the alley.
If you look at McCook, NE, on Google Earth, it is apparent that between many back doors and the "alley" there can be trees, shrubs, fences. These alleys run parallel to the north/south running streets ( these are named numbers ), they really look like they are just as effective at getting someone from the east/west streets ( these are named letters) as McCook's streets are. I have not seen it said this was directly out the back door in the alley. If perhaps, it is say in the middle of the alley, established the house on the corner, it might not be the first place everyone looks.
From another web site on the internet-
http://www.co.red-willow.ne.us/-I have discovered the avg. lot size in McCook in 140 ft., again and again I am seeing the avg. house size is about 50 ft. give or take. Simple math says that gives you 90 feet to work with on the lot, depending on where you place the house on the lot, how big your front yard is to the back yard, if you want 100 feet directly out the back door you are not going to get it, you have to turn one way or the other. Also, with this house being a corner lot there is only one way to go.
My deepest Sympathies and Prayers to the Clapp family.