MOO, I think the FBI had a long conversation with this person, may have searched the home and certainly the property. As I've seen in pass cases, the FBI shares little.
I would imagine all friends and family of these two have been extensively questioned by FBI. They have extensive resources, behavioral/profile analysis, the best surveillance equipment, surveillance aircraft, and the FBI lab is just up the road in Quantico.
The manhunt is on with dedicated, diligent LE, a tight small community and the FBI. They will be found. It may not be quick due to the vast challenging terrain, but I believe tbey will be found.
JMHO