Attorneys for the family of a 17-year-old student found dead in a rolled-up gym mat at a southern Georgia high school called on authorities Thursday to release surveillance video that they say could show what happened.

Kendrick Johnson, they allege, was slain in January - counter to authorities' conclusions that the three-sport athlete suffocated in the mat while reaching for a sneaker.

"There is one eyewitness that we know is available - it is the video recordings made from surveillance cameras there in the gymnasium where the body was found," attorney Chevene B. King Jr. told reporters in Valdosta, Georgia.