My teachers tell me to avoid the passive voice. I would say that the teacher (whose political views are irrelevant) was assaulted by a protester who pulled her hair and damaged her neck. I have not been able to find out if the college or police determined who it was or if they were prosecuted. The New York Times reached out to some Middelbury students and published their views on the incident. https://www.nytimes.com/2017/03/07/opinion/discord-at-middlebury-students-on-the-anti-murray-protests.html