Newly released surveillance video shows Chicago police dragging a high school student down a flight of stairs before striking and kicking her and using a stun gun.

Chicago Public Schools student Dnigma Howard's attorney, Andrew M. Stroth, said Friday that the video contradicts statements the two officers made saying the 16-year-old initiated the January altercation. She was charged with felony aggravated battery. Those charges were later dropped.

Dnigma's father, Laurentio Howard, on Thursday filed an amended federal civil rights lawsuit against the city, the Chicago Board of Education and the officers. The city's Law Department says it doesn't comment on pending litigation. The school districttarget="_blank"'>