Attorneys Benjamin Crump and Chevene King told the media they believe the surveillance video given to the family was edited, and the time stamps removed.
In January, Kendrick Johnson's body was found in a rolled up gym mat in the gym of Lowndes High School.
An initial autopsy ruled Kendrick Johnson accidentally suffocated in the mat. A second autopsy, conducted by a pathologist hired by Johnson's family, found he died from a blow to the neck.
There were 36 cameras inside and outside Lowndes High School. The video was released as a result of legal action, filed by his family.
One clip shows Johnson in the gym. A second shows Kendrick Johnson walking in, then running out of the frame. In both videos, students suddenly appear.
The family and attorneys are convinced the video was edited and manipulated.
An attorney for Lowndes County Sheriff Chris Prine said the video was not altered or edited by anyone within the sheriff's office. An attorney for the school likewise said that what was provided to the sheriff's office was the raw feed, with no edits.
Last week, a prosecutor said federal authorities will investigate the circumstances behind the death of Johnson.