Stacy Peterson, 23, of Bolingbrook, Ill., told her sister just one day before she disappeared that she feared for her life, The Chicago Tribune reported Friday.
Suzan Robinson said Stacy Peterson described her husband, Drew, as "a very jealous, very controlling person."
"He followed her. Tracked her with GPS on her cell phone, called her constantly," Robinson told The Tribune.
Thursday Illinois State Police executing a search warrant seized computers and cell phones from the Peterson house, The Chicago Sun-Times reported.
Police used cadaver dogs to search the house and later took them to an airport to help dive teams searching a nearby pond.
Police have said little about the searches except to report that investigators have found no signs that Stacy Peterson was the victim of foul play, the Tribune said.