The confession is not enough
Lena’s inability to lie means she says what she believes. It does not prove that her belief about the killer is correct. Reconstruct what she was made to witness.
Demo
Psycho-Sleuth · First case: answers & story
The furnace, the fragments and the gap between an honest confession and the actual sequence of events.
Reveal answers and story
Do not overread the bones
Incomplete fragments cannot reliably establish which side of the body they came from. Do not build the entire reconstruction on the assumption that only the apparent right-side remains matter.
Check both furnace compartments
The upper and lower spaces serve different roles. Lena is concealed alive in the lower chamber; do not assume that everything inside the furnace was burned together.
Reconstruct the coercion
Kizuna stabs the victim and places the body in the furnace. With Lyle held hostage, Lena is made to close her eyes and operate the furnace, believing that she killed a living victim. The belief and the physical killing do not coincide.
The message and the hiding place
After the furnace cools, Lena is forced to write the message inside the lower chamber. Kizuna knocks her unconscious and hides her there. Separate the time of the writing from the time of death.