No one murdered Maddie in School Spirits. Her body is still alive and well in the actual world. Maddie had suffered from a textbook case of bodysnatching.
All of this happened because Maddie was in the wrong place at the wrong time. While she was still alive, she happened upon Josh Zuckerman’s Mr. Martin (who has been counselling all the lost souls) and Janet’s spirits, who were both furiously bickering.
Maddie never gets the chance to figure out what she is walking into as Janet, a spirit everyone thought peacefully passed on, sprints into her—swapping places with her spirit.
Janet’s spirit now resides in Maddie Nears’ living body, while Maddie’s spirit is trapped in the Afterlife.
The season concludes with a cataclysmic schism between Maddie and Simon, who feels she is nothing more than a fabrication of his imagination.
To make matters worse, Janet, in Maddie’s body, is now on a bus bound for an unknown location. After remembering all of these horrific discoveries, the real Maddie is left standing face to face with Mr. Martin.