"According to the six-count indictment, from August 1 to August 5, Sterling Roberts cyberstalked Robert Caldwell via cell phone through the assistance of Tawnney Caldwell," reads the press release.
The firearm used in Robert Caldwell's murder was possessed illegally by Sterling Roberts, who "traveled interstate to stalk and murder Robert Caldwell," according to the FBI.
The charges against Tawnney Caldwell, Deakin, Christopher Roberts and James Harmon relate to aiding and abetting the illegal gun possession.
Tawnney Caldwell is also accused of destroying contents and data of a cell phone.
"Tawnney Caldwell and Chandra Harmon also allegedly conspired to intimidate and threaten witnesses related to the case in November 2017," reads the FBI media release.
Other charges in this crime include stalking, with a potential sentence of up to life in prison; discharging a firearm during and in relation to a crime of violence (death penalty or life in prison) tampering with evidence (up to 20 years in prison) and tampering with a witness by intimidation (up to 20 years in prison).
Sterling H. Roberts has been in custody in South Carolina since August 2017. The others were arrested in late February 2018.