Only the girls' bathrooms have locks. Kyoko points out that the killer had to dismantle the doorknob with a toolkit to reach Sayaka, something Makoto wouldn't have needed to do in his own room.
Sayaka’s dying message written in blood on the wall. When viewed upside down, the numbers spell "LEON".
Watch the high-stakes first class trial and the brutal consequences for the culprit in this episode:
Evidence reveals Sayaka initiated the room swap to lure a victim into her room, intending to frame Makoto for the murder to ensure her own escape. The Culprit Revealed
The trial begins with the group suspecting Makoto Naegi because Sayaka’s body was found in his bathroom. However, Kyoko Kirigiri assists Makoto in proving his innocence by highlighting key discrepancies:
The killer used a crystal ball to throw a bloodied shirt into the incinerator from a distance—a feat only someone with Leon’s athletic precision could achieve.
Leon is unable to produce his personal toolkit, which was used to unscrew the bathroom door.