The FBI has contacted Mexican authorities as the search continues for Nancy Guthrie, the mother of "Today" co-host Savannah Guthrie.

Law enforcement sources who spoke with CBS News said that federal officials are coordinating closely across the southern border, utilizing dedicated FBI border liaison agents who work directly with Mexican law enforcement on cases with potential cross-border implications.

The FBI's legal attache office in Mexico City is reportedly serving as a critical link between FBI headquarters, the U.S. Embassy, and Mexico's federal attorney general's office.

One source told CBS that the FBI suboffice most relevant to the Guthrie case is located in Hermosillo, Sonora — the Mexican state that borders Arizona.

Tucson is about 60 miles from the Nogales crossing, while Hermosillo sits roughly 170 miles south of the border.

Sources said that when incidents occur within this geographic corridor, the suboffice typically takes the lead.

Pima County Sheriff Chris Nanos has stated there is no indication Nancy Guthrie was taken into Mexico. Still, authorities are not ruling anything out.

One source told CBS that established border protocols are already in place for situations like this, even without a confirmed cross-border lead.

Meanwhile, a well-known local organization, Madres Buscadoras de Sonora (Searching Mothers of Sonora), confirmed to CBS that a member of the Guthrie family contacted the group seeking assistance with the search.

The organization posted a message on social media seeking information about Nancy Guthrie's whereabouts.

The 88-CRIME tip line reward climbed Wednesday to $102,500, including a $100,000 anonymous donation, the organization said, for information leading to the arrest of the person or people responsible for Nancy Guthrie's disappearance.

That amount is in addition to a separate $100,000 reward offered by the FBI as authorities seek answers.

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