You are most likely doing it wrong, since that stuff was added a year ago and not many people actually had issues aside from getting stuck.
But that's user error.
Anyway.
The staff, you find contradictions and confront them about it.
Dhena said Ami was illiterate, but if you check her room you find a diary. Confront Dhena with the diary evidence.
Erica said she was reading outside under the tree, but Emmet sprayed it with poison. Confront Erica with Emmet's evidence.
Ard said he heard a woman talking to Ami, but after confronting Erica she mentions hearing a man talking to Ami. Ard with Erica's evidence.
Hana claims she didn't hear anything but one of the other evidences points to her, I forgot...