Very well. Mystery #6 is fully solved!
After Alfred unintentionally freed Lucy from the Surveillance Camera Room, he ran away and locked himself in another room on the same floor. Lucy went back to the Camera Room, shut down the electricity, returned to the room where Alfred was hiding and pretended that she went to chase someone else. But in reality, she crawled under the room's window and waited until Alfred came close to inspect the hallway. Lucy then jumpscared Alfred by showing herself through the window in the dark (his 2 biggest fears were darkness and witches). This reminded Alfred of his old times in the inquisition and his heart problems returned. He also started to feel intense pain from his wounds on the cross, so eventually he dropped his masterkey. While Alfred was busy with taking his medicine, Lucy reached in for the masterkey through a small hole, retrieved the key, unlocked the door, entered the room, killed Alfred, left the room, and locked the door from the outside. Later when you found the butler, you assumed that you found Tina.