United States Attorney for the Middle District of Georgia Michael Moore launched the investigation in October 2013 to determine whether the teen's death involved any "interference with federally protected activities" and if there was an element of conspiracy, according to the documents provided to CNN by the Lowndes County Superior Court. However, DOJ's investigation has "expanded" to investigate claims of witness harassment and obstruction of justice.
The teen's parents never believed the local authorities' explanation that Johnson, 17, got stuck in the mat after diving in to retrieve a shoe. The state medical examiner concluded Johnson died as the result of accidental positional asphyxia. His parents, Kenneth and Jacquelyn Johnson, later had his body exhumed. They hired a pathologist who found evidence of "unexplained, apparent nonaccidental blunt force trauma" to the neck and concluded his death was the result of a homicide.
In January, Johnson's parents filed a $100 million civil lawsuit against dozens of local and state officials and named, among others, former schoolmates Brian Bell, Branden Bell and the Bells' father, FBI Special Agent Rick Bell, as defendants of a wrongful death claim.
According to an attorney for the Bell family, the three received letters in 2014 indicating they are also the targets of the federal investigation. The Bells adamantly deny any involvement in Johnson's death.
'Necessary for the United States to intervene'
The new details of the federal investigation come as part of two motions filed by DOJ aimed at blocking discovery in the civil lawsuit. Heavily redacted versions of the motions were released in October -- but after the judge denied DOJ's request earlier this month, the full documents were obtained by CNN.
In the filing, Assistant United States Attorney J. Thomas Clarkson cites the obvious evidence and potential witnesses the civil case and the criminal investigation have in common.
The documents also indicate that the Johnson's lead attorney, Chevene King, recently asked DOJ to allow Rick Bell to testify about matters that could include official DOJ information during a planned deposition. In response, Bell's attorneys asked Assistant United States Attorney Deborah Sines, who is heavily involved in the DOJ investigation, to return items collected as part of the federal investigation.
Attorneys deemed the evidence necessary to defend against the civil claims, according to the filing. There are no specific details of the evidence. The Bells' attorneys also asked for documents collected by a consultant hired by DOJ to assist in the federal criminal investigation.
For those reasons, "it became necessary for the United States to intervene," Clarkson wrote.
The filing includes the six-page affidavit from Criminal Investigator Nelson Rhone. According to Rhone, allowing attorneys to depose witnesses and collect evidence as part of the discovery process at this juncture would, among other things, "seriously jeopardize the federal investigation" and would "prematurely alert subjects of the federal investigation to evidence against them."
Rhone also claims that allowing discovery would have a "chilling effect on witnesses who have yet to testify before the grand jury and may result in additional witness tampering."
According to the filing, while the case has "yet to ripen into an indictment, the investigation into potential criminal violations is ongoing and is still an active investigation."
The filings do not offer a specific basis for any of the potential violations the DOJ is investigating.
Moore, who launched the investigation in October 2013, tendered his resignation to President Barack Obama earlier this month. His last day at the post will be November 23. The investigation has been transferred to United States Attorney Steven Dettelbach in the Northern District of Ohio.