(CBS/AP) EVANSDALE, Iowa - Investigators say they have evidence that leads them to believe two Iowa cousins who vanished last week are still alive.
FBI spokeswoman Sandy Breault said Saturday that authorities strongly believe 10-year-old Lyric Cook-Morrissey and 8-year-old Elizabeth Collins have not been killed.
"We believe," Breault said, "these girls are alive and we are not discouraged by the passage of time since their disappearance."
She refused to say what led authorities to that conclusion, but told reporters that investigators are expanding their search beyond Iowa.
The announcement came a day after authorities said they believe the girls were abducted.
Breault also said that while authorities have not received total cooperation from every family member and friend they've spoken to, "the majority of the family has cooperated 100 percent."
The girls vanished July 13 while riding their bikes near Meyers Lake in the northeast Iowa town of Evansdale. Their bikes were later found on a path near the lake.
Breault says investigators are interviewing "persons of interest" in the case, whom she declined to identify.