(CBS/AP) DES MOINES, Iowa - Local authorities are now draining Meyers Lake, located in the northeast Iowa city of Evansdale in a frantic attempt to search for clues in the disappearance of the two missing Iowa cousins. This is where the bicycles of Elizabeth Collins and Lyric Cook-Morrissey were found.
Elizabeth, 8, and her 10-year-old cousin, Lyric, were last 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 the lake.
Hundreds of volunteers took a massive sweep of the area over the weekend, but authorities suspended that effort Monday saying it failed to produce significant leads. With the heat and people going back to work, authorities decided not to do another large-scale search.
"Right now, we don't feel putting more civilians on the street looking for us is going to be a benefit," said Black Hawk County Chief Deputy Rick Abben.
Instead, rescue teams searched the lake by boat again Monday morning and began the draining process in the afternoon. Officers reportedly stopped cars at a number of intersections in town, questioning some drivers and searching trunks while others passed out fliers about the girls.
Abben said draining the nearly 5-acre lake could take up to three days. Officials believe it will go faster due to the low level of the lake and the Cedar River into which it drains.
Authorities previously scoured through the lake and interviewed family, friends and registered sex offenders who lived in the area, which led to no new information.
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."
He said the decision to drain the lake was made to rule out with 100 percent certainty that the girls are not in the water. Once that's done, all resources can be used elsewhere.
FBI spokeswoman Sandy Breault said the agency was working to put up billboards of the missing girls, as well as sending in tracking dogs to search in the area where the girls went missing.
Abben said the case is still considered a missing persons investigation and there was nothing to suggest the girls left Evansdale or had been abducted.
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