The families of two missing Iowa cousins say their worry that the young girls might have been abducted is growing as a search of nearby lake winds down.
Authorities drained the lake Tuesday after FBI dogs detected the girls' scent near where their bicycles were found four days earlier. They said once Meyers Lake is drained, they can focus their attention elsewhere.
FBI spokeswoman Sandy Breault said the reaction from the dogs Monday night indicated a "strong possibility" the girls had been at the lake, less than a mile from their grandmother's house where they were last reported seen Friday. However, Breault said because there were no confirmed sightings at the lake, authorities couldn't be certain.
Chief Deputy Rick Abben of the Black Hawk County Sheriff's Office said the case was still considered a missing persons investigation.
Elizabeth Collins, 8, and her cousin, Lyric Cook-Morrissey, 10, were last reported seen Friday afternoon leaving their grandmother's house. Their bicycles and Elizabeth's purse were found later that day near a bike trail at the edge of Meyers Lake in the northeast Iowa city of Evansdale.
Black Hawk County Chief Deputy Rick Abben said local, state and federal officials have been "grasping for straws" in the frantic search. A tip line turned up numerous reports of articles of clothing that had been found, but none belonged to the girls. He said it was as if they had just disappeared.
"It wouldn't be proper for me to stand here and tell you we have a theory because we don't," he said. "We have two missing girls, and we have no idea why."
Over the weekend, 1,900 volunteers and crews from various law enforcement agencies searched 12 square miles around where the girls went missing, The Des Moines Register reported. But the search yielded no clues into their disappearance.
Authorities stopped cars near Meyers Lake in 95-degree heat and searched inside the backs of vehicles and checked trunks, the Register reported. All sex offenders in the area have been cleared after talking with police, the report said.
The Associated Press contributed to this report