If habitability is the issue, it might be a stretch.
Finding what you suppose are remnants of blood is probably not enough to work.
However, you state the room does not meet requirements for a habitable room, without specifying any conditions. Suffice it to say, that if you are right, that would give you grounds to leave. Remember, the landlord HAS to be given notice to correct the defect.
Consult with a landlord-tenant lawyer in your area about this issue for more details.
Answered on Dec 26th, 2015 at 9:05 AM