Authorities are considering scaling back their search for a missing Montana teacher who left her home for a pre-dawn run and never returned.

The only publicized clue into 43-year-old Sherry Arnold's disappearance Saturday was a single running shoe, found by a ditch along her running route in her hometown of Sidney, near the North Dakota border.

FBI agent Deborah Bertrand said late Tuesday that tips were starting to come into an automated hotline set up for the case, but would not offer any details.

Hundreds of residents, police, firefighters and others have been combing the town and surrounding countryside, but Bertrand said the operation may shift gears Wednesday, with authorities going door-to-door seeking information.

The FBI and local law enforcement are investigating the possibility that Arnold was abducted.

Associated Press