The teen is charged with one count of criminal homicide and is being held without bond at the Rutherford County Juvenile Detention Center.
Josh DeVine with the TBI said in a news conference it is unclear if Farrar was directly targeting something or something.
“We’re looking at anything and everything,” he said.
Authorities also stated several weapons were found inside the home he was staying. It was not immediately if any were related to the shooting.
Devine added that Farrar attended school in the Springfield area, but was kicked out for a drug offense.
SFC Braden, from Ripley, Tenn., was a Readiness Non-commissioned Officer (NCO) who coordinated day-to-day activities and schedules at the armory.
He joined the Army National Guard in 1987 and was deployed twice to Kuwait with a transportation company out of Brownsville.
A graduate of Ripley High School, SFC Braden is survived by his wife Jennifer and their three children.
On Thursday, Governor Bill Haslam released the following statement regarding SFC Braden’s death:
“Sergeant Braden was a 27-year veteran of the Tennessee Army National Guard, and it’s a tragic day when we lose a decorated hero who has served his country so well. Crissy’s and my thoughts and prayers are with his wife, Jennifer, and their three children during this difficult time.”
News 2 talked exclusively with Farrar's aunt, Rebecca Chambers, who said her heart goes out to the victim's family, but she does not believe her nephew is behind the senseless act.
"We will leave it to the investigators to do their job and hopefully find the right person. I just can't believe that Christopher is responsible for this,” Chambers said.
She explained Farrar was living with her and his grandmother for the summer.
Chambers last saw her nephew around 3 p.m. Wednesday as she was leaving for work. Another relative called her shortly after to inform her of the shooting.
Chambers told News 2 she then called Farrar and told him to check on his grandmother and make sure the home was locked. It is unclear if she spoke to the teen or left a voicemail.
Police then later identified Farrar as a person of interest and, according to Chambers, told them they are certain he is the suspect.
"This is the last thing I would ever expect for Christopher to do," said Chambers.
The town of Lobelville only has around 1,000 people, so many knew either SFC Braden or Farrar personally.
Everyone is shaken up by the shooting.
Johnathon Smith, who works at Harley’s Restaurant, said Sgt. Braden came in often.
“He would always sit right there,” Smith pointed out. “He was always really nice and really police, and whenever he would come in here he was always really nice to talk to.”
Carley Hensley met Farrar in fourth grade before he moved to Adams, Tenn.
“He didn’t show any behavior like that when we were younger,” she told News 2.
The investigation is ongoing and a motive has yet to be determined.