Sorry to bump this old thread but I did go to this location recently. The blood letters are probably not actually blood but I dunno what it's for regardless.
The rest of the area is really cool but the main house is really hard to get into now. I got into the main building in 2015 when it was easier to break in and it was quite a creepy place. There were hundreds of files about monkey semen viscosity scattered throughout the building, broken glass everywhere, taco bell drink cups from the 90s and I swear I found a spooky doll in the basement but I can't find those old photos
Blood letters:
https://imgur.com/gallery/l3SuzRV Rest of the area:
https://imgur.com/gallery/P8ZBQFn