Iowa authorities said there was no new information on the two cousins who disappeared two weeks ago and decided to cancel a daily briefing because there is little new information to release on the case.

Black Hawk County Chief Deputy Rick Abben said Tuesday that investigators leading the search for 10-year-old Lyric Cook and 8-year-old Elizabeth Collins will provide any updates from now on directly to the media through email or fax.

He says the decision does not mean investigators are in any way scaling back the search for the girls.

"We're not giving up," Abben told The Des Moines Register. "We've still got two missing girls and we aim to find them."

The Register reported that a store security camera in Evansdale showed the girls riding bikes just after noon on the day they disappeared. They were apparently riding near a relative’s home. Their bikes were later recovered by authorities near Meyers Lake.

Wylma Cook, the girls' grandmother who was baby-sitting them at the time, said she didn’t know how the girls ended up across town by the lake.

"It shocks me, OK. The girls never rode that far, never. It was in a two-block area, that's it. They always returned like I told them," Cook said.

An extensive search involving local, state and federal investigators has failed to find them. FBI spokeswoman Sandy Breault said there was "nothing new" about the case Tuesday.

Breault stood by her assertion, first made Saturday, that investigators believe the girls are alive.

"They are not going to reveal the reasons why. You wouldn't want them to do that. It would jeopardize the investigation and the children," she said.

David Finkelhor, director of the Crimes Against Children Research Center at the University of New Hampshire, said that claim means investigators could "have something quite important" for evidence.

He said cases of two children being abducted by a stranger were rare since it would be hard for one person to control both, which makes the common motive of sexual gratification less likely in this case.

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The Associated Press contributed to this report