I think the inspector is suspicious because of how he discusses the case so openly, like when he went to question pued, he did so in front of pueds dad. And he didn't treat pued as a suspect even tho he should. it seems like there's a bunch of people behind this and the inspector/police are also involved. Their meeting place could be the club because of that one time the inspector invited bun to go with him then he disappeared to go talk with his "friends" (when the girl asked him to join them) and Tan was coincidentally there too. at this point, everyone is sue to me.