Federal agents and Iowa investigators say they are studying data subpoenaed from Mollie Tibbits' Fitbit account. The 20-year-old University of Iowa student has been missing for a week. FBI and Iowa Division of Criminal Investigation agents are working with the Poweshiek County Sheriff's Office in the search for Tibbetts. She disappeared after dog sitting in Brooklyn, Iowa a week ago Wednesday. Investigators say they cannot rule out abduction.