Story highlights Records: Sheriff's investigators did work this month on Kendrick Johnson death case

Sheriff's office said it closed the case 18 months ago

Johnson was found dead inside a rolled-up gym mat

Investigators found it to be accidental; the Johnson family believes it was a homicide

Despite concluding there was no foul play in the death of a Georgia teen nearly two years ago, a sheriff's office conducted additional interviews on the case as recently as this month.

The parents of Kendrick Johnson, who was found dead inside a rolled-up gym mat at his school in Valdosta, Georgia, have been unwavering in their belief that their son was murdered, even after the Lowndes County Sheriff's Office ruled the death accidental and closed the case 18 months ago.

The details of the recent interviews, conducted by the sheriff's office between November 24 and December 15, were provided to CNN in response to a public records request.

The sheriff's office interviewed about two dozen current and former Lowndes High School students who were on the school's wrestling team on January 10, 2013, the day Johnson disappeared. His body was found the next day.

The additional interviews appear to be related to a video released by attorneys for Johnson's family that challenged the whereabouts of one particular former student who was on the wrestling team.

According to investigative records, the former student confronted Johnson and told him "it ain't over" regarding a confrontation Johnson had with the former student's younger brother.

CNN is not naming the former student because he has not been called a suspect or been charged with a crime.

The former student would have been at a wrestling match in another city at the time Johnson is believed to have died, but lawyers say the bus did not leave Lowndes High School until after Johnson's death.

An attorney for the sheriff's office confirmed the recent interviews, but did not respond to a question about whether the case has been reopened.

"The Lowndes County Sheriff's Office initiated the interviews of the Lowndes High School wrestling team coach, the bus driver and wrestling team members in response to claims made known to the sheriff's office that the wrestling team was still on the school's campus when Kendrick Johnson was last known to have been alive," according to a statement provided by the department's attorney. "Investigators have tried unsuccessfully to contact some wrestling team members and will continue to attempt to reach those team members."

The statement added that the interviews so far have not changed the facts believed by the sheriff's office.

"The information gathered thus far indicates that the bus carrying the wrestling team had left the school's campus prior to the time that Kendrick Johnson was last known to have been alive," it said.

Several of those interviewed said the former student was on a school bus en route to a state tournament in Macon, Georgia, the day Johnson disappeared. Others could not say for sure.

However, there are inconsistent accounts about when the bus left the school.

Some of the current and former students told investigators the team left campus before 10 a.m. Other students said the team left just before noon. The bus driver told investigators the team left at 12:30 p.m., according to incident reports.

According to a school bus schedule provided to CNN by an attorney for the school, the bus left for the tournament at 4 p.m., hours after Johnson was last seen alive around 1:30 p.m. The wrestling coach told investigators the school bus schedule was inaccurate, as it reflected a request made by him at the beginning of the wrestling season, and not the time the bus left on the actual day of the wrestling meet.

Analysis of the coach's cell phone bill showed the last call that accessed a tower in the Valdosta area that day occurred at 11:28 a.m. At 1:53 p.m., the phone accessed a tower in Cordele, Georgia, nearly 90 miles outside of Valdosta.

An employee at Candlewood Suites in Macon told investigators the coach checked in for the team at 4 p.m., according to incident reports.

One student told investigators that the weigh-in for the team began at 4 p.m., according incident reports.

According to a document included in the investigative file, the former student participated in the weigh-in on January 10, but when that weigh-in occurred is not indicated.

Previously released documents showed that the former student and his brother were advised by their attorney in 2013 not to speak to investigators or provide them any statements.

In August, the brothers' parents filed a $5 million libel lawsuit in federal court against the publishers of Ebony magazine and writer Frederic Rosen. The suit claims stories written by Rosen and published in Ebony magazine and on Ebony.com imply that the brothers played a part in Johnson's death and their father was involved in a conspiracy to cover it up. The claim that the brothers played any part in the death "is completely untrue," according to the lawsuit.

The interviews come more than 18 months after Lowndes County Sheriff's Office closed its investigation into Johnson's death. Sheriff's office investigators concluded Johnson got stuck while reaching for a shoe at the center of the rolled mat. The state medical examiner determined Johnson died as the result of accidental "positional asphyxia."

Johnson's parents, Kenneth and Jacquelyn Johnson, believe the story about the shoe is a cover-up and that their son was murdered. A forensic pathologist hired by Johnson's family later found evidence of "unexplained, apparent nonaccidental blunt force trauma" to the neck. He concluded Johnson's death was the result of a homicide.

A federal investigation into Johnson's death, launched more than a year ago, continues.

The Department of Justice has taken possession of the gym mat where Johnson's body was found, according to the records released by the sheriff's office to CNN.

Last month, the approximately 6-foot gym mat was rolled in brown paper and loaded into a vehicle driven by Assistant U.S. Attorney Deborah Sines and U.S. Attorney's Office Criminal Investigator Nelson Rhone Jr., according to the documents.

Federal authorities also reviewed evidence being stored as part of the case and were given copies of three discs with audio recordings of calls for service made the day Johnson's body was found and two discs with video surveillance.