I don't think the author knows
Well, I think that when the high priest tested the paper, in front of an audience, it revealed that the true culprit was Beatrice, not Raeliana. But Raeliana was unconscious at the time, so she wasn't aware of that. She still thought people considered her as the culprit. That's why she thought she had to run away, until her name was cleared. But when they discovered Beatrice's body, they knew that Raeliana killed her because of self defense, and not to get rid of a witness. I hope this answers your question
Thank you (๑•ㅂ•)و✧
Wait how did they clear the problem with Beatrice? The chapter when Raeliana thought they were going to catch her for killing Beatrice so she had to run away