Crushkill, if you had killed Maria at a higher rep => the guards would not attack you. I tried this myself as an experiment => attacked her - she called for help, a few guards came to aid. Funnily enough only those attacked, others entering the house did not (the ones walking around there); simpl,y stood foolishly around - and I took care not to kill them, only the attacking ones. As she had fled out of the house, I cornered her outside to kill. No normal guard attacked me. My rep went down - but it was too high to trigger guard hostility later on.
Kiya