A dive team using sonar equipment will search a northeast Iowa lake for evidence of two missing cousins who disappeared nearly a week ago, an FBI spokeswoman said Thursday.

Sandy Breault said the team will begin the search of Meyers Lake in Evansdale around 6 a.m. Friday. Authorities stopped draining the lake Thursday because the team's sonar equipment needs at least 6 feet of water to function properly. They previously said they wouldn't finish draining the lake until Friday.

The team uses two kinds of sonar — one that can detect debris in murky water and another that provides a 360-degree analysis of the bottom of the lake. That device is mounted on a tripod that sends signals to computers on the surface helping direct divers where to search.

The dive team is equipped to go into the deepest parts of the lake, which may be as deep as 20 feet.

Eight-year-old Elizabeth Collins and 10-year old Lyric Cook-Morrissey were last seen Friday leaving a house in the Waterloo suburb where their grandmother was watching them.

Family members of Elizabeth Collins, 8, and Lyric Cook-Morrissey, 10, are pleading for more help in finding the girls, last seen Friday leaving the house in the Waterloo suburb of Evansdale, where their grandmother had been watching them, less than a mile from Meyers Lake.

"We're at a standstill," Tammy Brousseau, an aunt to both girls, told The Associated Press. "Bring in everybody. Bring in the Army. Let's do this manhunt again. ... They disappeared into thin air."

U.S. Rep. Bruce Braley said the girls' family asked him to send a letter to FBI Director Robert Mueller seeking assurance that all available agency resources were being used.

Brousseau said she feared the girls were abducted, possibly by a sexual predator. She dismissed the possibility that the girls might have drowned in the lake, noting they are good swimmers and that their shoes weren't found.

Authorities dredged the lake, then began draining it on Monday in hopes of ruling out that the cousins had died in the water. The effort was taking longer than expected, but Black Hawk County Chief Deputy Sheriff Rick Abben said.

On Monday night, FBI dogs detected the girls' apparent scents in the area, and officials said that signaled a strong likelihood they had been there.

Debbie Acklin, of Black Hawk County Waste Disposal, said authorities asked the company Monday to start dumping trash from Evansdale homes and businesses in a separate area of the county landfill. Abben confirmed the landfill had been searched but declined to say what, if any, evidence was found.

Brousseau said officers recently went into a family home and confiscated all the computers "for the purpose of seeing what information they could get off them." She did not say whose home the computers were taken from, and investigators did not comment on the removal of items from family members' homes.

While Lyric's parents conducted television interviews and frequently checked the lake, Elizabeth's parents stayed out of the public eye. Drew and Heather Collins have moved from their home in Evansdale to an undisclosed location to get rest because too many people kept showing up, Brousseau said.

Abben said the family was cooperating with the investigation.


Associated Press writer Nelson Lampe contributed from Omaha, Neb.