guidance councillor blames me

Question! How do you solve a problem when you are not around the situation? I had a "nice" confrontation with my daughters school councilor a few months back, telling me to do just that!
"Candra was seen sticking up the finger several times today."
"Where did she get that from? Who put her up to it?"
"It doesn't matter don't let it happen again."
How canI prevent something from happening when I am not there. I wasn't even told of any disciplinary actions towards Candra. 😠