Responses
I believe it's this manhwa, if not, hope you find it! ^^
https://www.mangago.zone/read-manga/the_killer_s_interview/
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It was a manwha about a young detective whose parents were killed by a murderer and he has this book that opens to hell and all the serial killer are there he talks with them to solve other cases few of them were ted bundy, madame brinvelliers