A former FBI agent believes there is still evidence left unturned five months into the Nancy Guthrie case.

The search continues for Savannah Guthrie‘s 84-year-old mother, who vanished from her home just north of Tucson, Arizona on February 1. She was last seen at the property at around 9:30 p.m. on January 31 and was reported missing the next day.

As the FBI and Pima County Sheriff’s Department continue to field through over 40,000 to 50,000 potential leads and tips, a former special agent has suggested a new terrain to explore for clues.

Former FBI special agent Jennifer Coffindaffer said law enforcement should consider widening their search efforts into the surrounding desert areas. While speaking to The Express Tribune, she argued difficult landscape could still hold evidence missed in the beginning of the investigation.

The FBI and Pima County Sheriff’s Department previously carried out operations using drones, helicopters and search-and-rescue teams. They have also utilized surveillance footage and neighborhood camera systems to their advantage, which is how they found a video of a potential subject weeks after the incident.

Within a clip obtained from Nancy’s Google Nest, an individual was captured approaching her front door wearing dark gloves, a zip-up hoodie, a pair of sweats, a backpack and a balaclava.

Despite finding a visual of the potential subject, the authorities have yet to name a suspect or find Nancy.

Nancy’s family learned she was missing on February 1, when she failed to attend her local mass. Shortly after that, the Pima County Sheriff’s office deemed her home a “crime scene” after discovering concerning evidence inside the property.

Savannah has remained persistent in her search for her mother, with her family even offering a reward of up to $1 million for information on Nancy’s whereabouts.

The Pima County Sheriff’s Department also announced a separate $50,000 reward for any “information leading to the recovery, and/or the arrest and conviction of anyone involved in her disappearance.”

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