Claiming One's Life After Death: the Perfect Crime Designed by Mr. K

[Suspense + not brainless + fast pace + emotionless line + first perspective + reversal] Stack a buff: This book is purely played by hand and rejects AI I found a note left by "Mr. K" at the scene of the car accident, which actually involved three murder cases, which were fabricated as accidents, murders, and suicides. When the clues of "dead people killing people" gradually become clear, old events come to light, and the truth is about to emerge, they discover that "Mr. K" who is good at manipulating people's hearts is actually someone else. When all the clues are connected, can you guess who the murderer is until the end?