A federal grand jury investigating the 2013 death of high school teen Kendrick Johnson, who was found inside a rolled gym mat, have subpoenaed former schoolmates and their parents, according to sources with knowledge of the subpoenas, CNN reports.
According to a CNN source with knowledge of the investigation, the FBI—which launched an investigation four months ago after Johnson's parents brought national attention to the case and their belief that the original probe was mishandled by local authorities—have interviewed several of Johnson's former schoolmates from Lowndes High School in Valdosta, Ga.
"We're working methodically, and sometimes we remember we're running a marathon instead of a sprint," U.S. Attorney Michael Moore told CNN outside the federal courthouse.
"So, we're working on it. It's better to get it right than to get it fast. I'm satisfied that the FBI is moving forward at the appropriate speed, and they're doing a fine job."
On Jan. 11, 2013, Johnson's body was found in a rolled-up mat in the school gymnasium. The Lowndes County sheriff's office ruled his death accidental, claiming that in an attempt to retrieve a shoe from inside a rolled gym mat, Johnson fell in and got stuck.
State officials ruled Johnson's death as "positional asphyxia," or suffocation by his own body weight, CNN reports.
From the beginning of the investigation, Johnson's parents have called the official story a cover-up, contending that their son's death was a homicide.
Johnson's family commissioned a separate autopsy, which concluded that the 17-year-old died from "apparent non-accidental, blunt force trauma."
Since becoming involved with the case, the FBI have interviewed the Lowndes County sheriff, Chris Prine, and County Coroner Bill Watson has been interviewed twice. Lowndes County Schools said it was subpoenaed only to provide hard drives containing surveillance video from the school, CNN reports.
When asked if he found the fed involvement encouraging, Johnson's father, Kenneth Johnson, told CNN, "We really won't feel anything until justice comes for Kendrick. We're glad they're here, but my feelings won't be there until we get justice for our son."
Read more at CNN.