As a Ghost Exorcist, Investigating a Case?

Luo Fan and Luo Sheng are a pair of strange siblings. They join the investigation organization and threaten to catch ghosts. The brothers and sisters were very excited every time they encountered a strange case and made breakthroughs time and time again. But every time a bizarre case comes to light, no one sees the ghost the brother and sister talk about. "These cases have been solved, where is the ghost you are talking about?" "I really don't understand. How can you be so sure that there are ghosts in the world?" Both of them just smiled. They were ghost brothers and sisters. In order to practice, they devoured all the people around them. Ghosts, like humans, are social animals. They are close to the same kind, but none of them expected to be killed by this brother and sister. "If ghosts also have laws, brother, we will be doomed." (It's a mystery novel, no supernatural elements, but ghosts have longer lifespans)