(NewsNation) — The FBI has now taken cellphone tracking to the next level with a system called Cellular Analysis Survey Team, or CAST.

Former CIA and FBI agent Tracy Walder explained Tuesday on “Banfield” that towers around the University of Idaho campus could hold important clues about the whereabouts of the victims in their last few hours alive.

Walder has used cellphone towers to locate suspects in the United States and overseas, including terrorists.

She says the CAST technology works, and she’s “shocked we haven’t solved it (the case) because of the propensity of 20-year-olds to use cellphones.”

“I would think that that cellphone data would be very, very critical in terms of locating particularly Xana (Kernodle) and Ethan (Chapin), but on the flip side, an absence of data might also indicate a suspect, as well,” Walder said.

Moving forward, Walder believes that the technology could, at the very least, help identify a person of interest in the case.