But How Did They Know?

I have but one question after reading this:

Settlers Residents: Jerusalem high school teacher took part in violent left-wing protests

Parents at Jerusalem High School for the Arts complain about teacher identified in clashes between leftists, settlers local residents at a West Bank settlement of Anatot.

A Jerusalem high school teacher was among left-wing activists who violently clashed with residents [!] of the West Bank settlement community of Anatot two weeks ago, according to a recent complaint by the Mateh Binyamin Regional Council.

...At one point, the activists began hanging Palestinian flags and defaced a slogan that read "the Land of Israel for the Jewish people ["Am Yisrael"] by changing "Israel" to "Palestine."  Dozens of Anatot residents who saw what was happening came out and attacked the group of activists, consequently wounding some 20 leftists.

A resident of Anatot, who is the mother of one of the students at Jerusalem's High School for the Arts, apparently identified the teacher among the left-wing activists and filed a complaint with the school board.   The head of education at the Mateh Binyamin Regional Council joined the mother's complaint and urged the school board to rebuke the teacher.

...The Education Administration of the Municipality of Jerusalem rejected the complaints against the teacher.  "The teacher did not use violence and it is her full right as a citizen to take part in protests, even if such a decision does not bode well with some of her students," they said.

And my question is:

how did those administrators know she did not use violence?

How did they know?

Did they ask the police?

Did they believe the teacher?

or

Were some of the administrators there and witnessed the event?

Or, maybe they were the ones who were violent and themselves threw the rocks?

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