Investigators are faced with a "huge obstacle" as they scramble to find a missing Kansas mom and a preacher's wife, according to experts.

Authorities are searching for Veronica Butler, 27, and Jillian Kelley, 39, after their abandoned vehicle was found on the side of the road Saturday in Elkhart, Kansas – about 15 miles away from their intended destination of Eva, Oklahoma.

The pair were reportedly on their way to pick up Butler's children when they disappeared.

Former FBI Agent Jennifer Coffindaffer said the difficult terrain where the women vanished will likely make law enforcement's job more challenging in tracking them down.

"A huge obstacle for law enforcement is the ruralness," Coffindaffer told NewsNation Wednesday.

"I grew up in Kansas," she added. "We always teased that the national tree was the telephone pole. There is nothing there. That's going to limit the capabilities of digital analysis of their cell phones."

Coffindaffer, who spent 25 years with the FBI, also pointed out that the custody battle Butler was reportedly in the midst of with her ex, sends red flags.

"Whenever I hear custody battle and see a mother go missing in this way, that is the number one action point I would begin at," she said.

"It's very concerning" the area they went missing could be a place for a "random strike," Coffindaffer weighed in. "In other words, if these ladies were harmed in any way, it is likely going to be someone that they know and are familiar with."

An unnamed source previously told the outlet Kelley – a preacher's wife – may have been accompanying Butler to act as a mediator when picking up her kids.

Butler's children may have been living with their paternal grandmother at the time.

Loved ones said law enforcement have instructed them not to speak with the media.

Coffindaffer said it's likely detectives will change their mind as the investigation continues.