From a strictly ‘lawful’ standpoint, any evidence he finds in his house right now cannot be used against him in court. But they also have him on site dumping a human body so there’s no denying that. That being said, I am basing my ‘lawful’ on US laws and I KNOW FOR A FACT there are countries that allow for ‘illegally obtained’ evidence, I’m just not sure about South Korea.
Edit: Welp, I’m super late because EVERYONE in the comments brought this up lol