CHICAGO (CBS) — Newly obtained video offers a new look at a disturbing altercation at Marshall High School between Chicago police and a student.

On Jan. 29, CPD officers were asked to escort 16-year-old Dnigma Howard out of the school following a confrontation with a staff member.

The video shows Dnigma starting to walk away from one of the officers when he grabs her and forces her towards the stairs.

Video from the floor below shows Dnigma and the female officer entangled on the stairs as the male officer appears to be dragging the girl down the stairs by one of her legs. Police say Dnigma tried to bite one of the officers. That’s when she says she was tased.

The family’s attorney says the video shows the officers lied about what happened, so he has amended their federal lawsuit against the city and the officers.

In response to inquiries about the video, a CPS spokesperson said the school district is deeply disturbed and troubled by the incident. Both COPA and the school district’s inspector general are investigating what happened

Charges against Dnigma were dropped in February.

The girl’s father said the whole thing was handled improperly.

“This case is about failed leadership at the Chicago Public Schools system.  It’s about failed leadership at Marshall High School,” he said.

He said he is appreciative the felony charges were dropped because his daughter has future plans to go to college.