I know you've probably looked, but I have been called to houses to look for snakes and we've found them in a pile of clothes on the floor. In the bed sheets, under a pillow too. If you have full length drapes, look there too. Inside furniture. Then you can look in/under/between anything that generates heat. Grab a bright flashlight and start looking inside,next to, under, anything that you can think of. However, don't jump from room to room. Take one room at a time and start in one corner and completely inspect all areas of that room. Only after you've checked everywhere in that room, should you go to the next.

Good Luck!
Jim Smith