Police Probe Use Of Pepper Spray During Protest

State police say they have begun an internal investigation after a Cambridge man posted an online video that appears to show a trooper using pepper spray on him.

Kin Moy says he was trying to record a man being arrested on a highway on-ramp last Thursday as several hundred people protested the killings of unarmed black men by police in Ferguson, Missouri and Staten Island, New York.

In the video (caution, it contains explicit language), the trooper appears to warn Moy to move away or he would be sprayed.

Moy says he backed away, but the video appears to show the trooper spray Moy three times. Moy then turns the camera on himself to show orange liquid on his face.

State police said it was conducting a "thorough and unbiased" investigation to determine if any departmental policy was violated.