OSAKA, Japan—Japanese police on Saturday searched the house of one of the patients at a mental clinic where a fire gutted an entire floor in an eight-story building, killing 24 people trapped inside. An Osaka police investigator told The Associated Press that the man is a possible suspect. A small fire broke out about half an hour before the building fire at the man’s house, where a patient registration card was found, the investigator said. He is believed to be among the three people who survived and were in severe condition. Police have not arrested anyone, and it may take a while until the man recovers enough to be interrogated. According to witnesses interviewed by Japanese media, a man walked into the clinic in downtown Osaka, carrying a paper bag, which he put on the floor, right next to a heater by the reception desk, and kicked it. A liquid …