A forensic video analyst said he's "suspicious" of newly released footage that authorities had hoped would help them in the case of a teen found dead rolled up in a wrestling mat.
The body of 17-year-old Kendrick Johnson was discovered in his high school gym in Valdosta, Georgia on January 11. Johnson's family believes he was killed.
This month, footage was released from video cameras that investigators had hoped would show what happened in Johnson's last moments.
But CNN spoke with forensic video analyst Grant Fredericks who said there are major flaws in the footage.
"(The surveillance video has) been altered in a number of ways, primarily in image quality and likely in dropped information, information loss," Fredericks said. "There are also a number of files that are corrupted because they've not been processed correctly and they're not playable. I can't say why they were done that way, but they were not done correctly, and they were not done thoroughly. So we're missing information."
Lowndes County Schools told CNN the video is "a raw feed with no edits," and the Lowndes County Sheriff's Office said it didn't edit any of the footage.
As the Associated Press previously reported, the sheriff's office originally ruled Johnson's death a freak accident:
The sheriff has said he suspects Johnson became trapped trying to retrieve a shoe that fell into the center of the large, rolled mat. A Georgia Bureau of Investigation medical examiner concluded that he died from positional asphyxia, meaning his body got stuck in a position in which he couldn't breathe.
But in October, a federal prosecutor announced he would re-open the case.
WXIA reported that Johnson's family is also "suspicious" of the footage. The family's lawyer told the station they plan to have their own experts look at the videos.