See the wall that comes out from the right - simply extend it across to the left and put a door in it.It would look normal, visually, and then everyone could use that storage closet under the stairs - perfect place to store winter clothes and stuff, X-mas decorations, etc.A non-load-bearing partition wall with a door in it to the downstairs "bedroom" should be pretty cheap. 

Kept it for several years until I got into rehabbing salt damp damaged bungalows with a few other guys, so I reluctantly sold it for about double.In 2012 my wife & I visited the city & most of the front yard had been expropriated to enlarge the road but the place was immaculate.  

@Alyssa Lebetsamer there is technically mold spores at some level many places that are damp or humid.

Keep in mind that the strong odor could just be on his stuff - his clothes, for example.

Blood ,feces everywhere and smelly clothes by the bushel basket to throw out .

I always embed hardware cloth into the hole for good measure before foaming it.If you catch one in a glue board, you can use vegetable oil to free it once outside without harming it.I've always used the snap traps with PB as @Victor S. suggests, but the most important thing is to find their means of access and block that. 

I have been flipping my old clothes and thrift clothes (really anything I could sell) since I was in high school and have found it to be a very effective way to make money if you play your cards right.

In 2012 I bough a Ionic AIr Purifier off Amazon for $50, and it worked great for eliminating odors off clothes and such.

Mold is very common in our area and 90% of the time there are small traces somewhere in the home due to the damp climate in our area. 

The tenant left multiple spots on the driveway where they spray painted home projects without a drop cloth, some spots are up to 3 feet long and turquoise in color.Also there used to be a drive thru gate to the back yard so you could back a trailer or RV in, they took that gate off and fenced across the opening.