Copus also questioned the handling of a pair of gym shoes that had a substance that appeared to be blood on them.
Investigators told CNN the shoes weren't collected as evidence because the substance was not blood.
Despite the findings of state medical examiners who found no evidence of foul play, a private pathologist hired by the family to conduct a second autopsy after exhuming the teen's body found that Johnson had a blow to the right side of his neck "consistent with inflicted injury."
The pathologist also discovered that the teen's organs had not been returned to his body after the initial autopsy. It had instead been stuffed with newspapers.
The absence of the organs fueled the family's suspicions of a coverup in their son's death.
"They know something happened in that gym, and they don't want it to come out," Kenneth Johnson said at the time.
For months, the family's quest for answers went nowhere. It took until May for autopsy results to be issued, and then the sheriff's office said the investigation had been closed.
The sheriff's office and school officials resisted the family's request to obtain school surveillance images and other records, citing state law that exempts the release of "education records of a minor child."
After months of pursuing official answers and getting nowhere, they began staging daily rallies.
A Facebook tribute page and a CNN iReport submitted by Kendrick's aunt spread the message far beyond the southeast Georgia town.
On Monday, a Lowndes County judge ruled that authorities had to turn over the surveillance records and files sought by the family -- the first step, family attorney Chevene King said -- in finding what they say is the truth about what had happened.
Video included in the release and reviewed by CNN shows him walking in a hallway and entering the gym.
It also shows him inside the gym prior to his death, along with other students playing basketball.
There is no indication that any of the people shown in the video have any knowledge of the events surrounding Kendrick's death.
A civil rights case?
King has alleged that if Kendrick had been white, the investigation would have gone differently. He doesn't believe race tells the whole story though.
"You have to consider race as a factor, but I don't think that that's the end-all in terms of trying to understand why this case was handled in the way that it was," he said Thursday.
"We believe that, certainly, if there is a coverup it is a coverup for somebody, and not a nobody," he said.
Prine, the sheriff, is white, as are about 60% of the county's residents. However, sheriff's office officials have rejected the claim that race influenced the case.
"Race never played into it," Stryde Jones of the Lowndes County Sheriff's Office said in May. "The victim played into it. That's who we're working for is the victim and the victim's family."
King said none of the materials released Monday are expected to show exactly what happened to Kendrick.
But they could cast doubt on the official explanation and nudge officials toward reclassifying Kendrick's death to allow a new investigation into what happened, King said.
"Essentially, it shifts the focus from what the sheriff had offered to other theories that were not explored and that have I think begun to slowly creep to the surface," King said after the hearing.
On Thursday, Lowndes County Coronor Bill Watson said he has not made a decision yet on whether to open a coroner's inquest into the death. That would be the first step in reclassifying the death to something other than accidental to allow a fresh investigation into the circumstances.