In the surveillance video, you see an adult leave out the back door, but it never closes.
A little more than a half hour later, 14-year-old Avonte can be seen running down the hallway at 12:03 p.m., pausing for a second, and then bursting through the door.
Three minutes later, the school attendance officer walks up and closes that door.
"The broadest way of speaking about it is never again. Don't let children leave school between bringing them to school and getting them home. They can't disappear," said David Perecman, the family's attorney.
The autistic teenager's family has already filed a lawsuit against the city and the Department of Education, claiming they did not take care of Avonte that day.
Avonte's body was found two weeks ago in Queens Village.