The Seventh Piece of Testimony

Ten years ago, the male lead's older brother was named the killer in a whole-family murder case, then "committed suicide." Ten years later, a serial killer leaves behind one puzzle piece with every murder. Put together, the pieces depict the scene of that old crime. Returning to the police station as a criminal investigation consultant, the male lead uses his crime-scene reconstruction skills to hunt the killer, only to discover that the real culprit has been hiding within the police force all along. Evidence never lies. People do.