DAVID PITT, Associated Press

EVANSDALE, Iowa -- Authorities searching for two young cousins drained an Iowa lake Tuesday after FBI dogs detected the girls' scents near where their bicycles were found four days earlier, heightening suspicion from family members that they might have been abducted.

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. The decision to drain the lake was made to rule out the possibility the girls were in the water, he said.

Officers slowly paddled around the lake in kayaks on Tuesday morning. A group of three officers walking along the southeast shoreline stopped to study something that appeared to be a cup. An officer with gloves and an evidence bag picked it up and took it back to a patrol car sitting along the bank.

Officials didn't identify the object or even confirm whether it was related to the search for Elizabeth Collins, 8, and Lyric Cook-Morrissey, 10, but it was a rare sign of activity in a massive search that has produced few if any significant leads.

"I don't think that they're in the lake not at all but it is just like a dead end as far as we know so far," said Dan Morrissey, Lyric's father. "We've never gone through anything like this. It's hard enough just to get up and deal with the reality that your daughter is gone."

Tammy Brousseau, 48, an aunt to both girls, said all the signs were pointing to a stranger - possibility a pedophile - abducting them from the area near the lake where their bikes were found.

Brousseau said that just last week she taught Lyric how to "save someone if they went limp in the water." She said she also taught both girls how to "drop to the ground and fight" if someone tried to abduct them.

Lyric's parents said they didn't suspect a drowning either, noting the girls' swimming abilities and the fact that no shoes were recovered on the bank of the lake.

"The area where the bikes were found is fenced on both sides, and it is right where maintenance gate is. It is a spot that looks to me like a trap," Dan Morrissey said. "Somebody could have just come along right then or followed them down it would have been the worst spot to be in right there."

At least 30 FBI investigators joined the search for the girls, who were last reported seen Friday afternoon leaving their grandmother's house in Evansdale. Their bicycles and Elizabeth's purse were found later that day near a bike trail at the edge of Meyers Lake.

Breault said the search has been slowed because of the time required to drain the lake. The draining began Monday afternoon and could take up to three days. But local officials said the draining likely will go faster because of the already low level of the lake and the Cedar River into which it drains.

The lake is draining through a 3-foot culvert with a grate over it that would prevent a body from flowing into it, Abben said. A pump was brought in on Tuesday to quicken the pace.

The lake was drained in 2008 when the area flooded and in 2009 when a fish kill prompted the city to empty it and restock it.

Abben said he was told it was down 3 feet on Tuesday morning and the water level continued to fall throughout the day with more of the bank visible.

A massive sweep of the area that drew hundreds of volunteers over the weekend failed to find any evidence. Authorities previously dredged the lake and have been interviewing family, friends and registered sex offenders who live in the area.

Abben said that local, state and federal officials have been "grasping for straws" in the 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.

Abben declined to talk specifically about evidence other than saying the bicycle and purse, which had a cellphone in it, did not definitely place the girls at the lake. The cellphone was used by the girls to play games and was not activated to make calls, he said.

He said tips were coming from across the United States since the story has gained national attention.

He said the family has been cooperating with the investigation.

"We have no reason to believe there was any foul play at this time," he said. "Everyone is suspect until we find something."

Lyric's mother, Misty Morrissey, said the family members were trying to stay as upbeat as possible considering the circumstances.

"We're pretty emotional, pretty sad, trying to remain positive and trying to hold on to our faith and know that God is still in control and we're going to find a resolution to this," she said.

___

Associated Press writer Ryan J. Foley contributed to this report from Iowa City and writer Grant Schulte contributed from Lincoln, Neb.

Loading Slideshow...
  • Lyric Cook-Morrisey Elizabeth Collins

    Lyric Cook-Morrisey (left) and her cousin, Elizabeth Collins, have been missing since July 13.

  • Lyric Cook-Morrisey And Elizabeth Collins

    Lyric Cook-Morrisey (left) and her cousin, Elizabeth Collins, were last seen July 13, when they left their grandmother's Evansdale, Iowa home and went on a bike ride. The girl's bikes and one of their purses were later found along a nature trail that runs along Meyers Lake.

  • Misty and Dan Morrissey speak to the media near Meyers Lake where their daughter Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Elizabeth Collins

    Eight-year-old Elizabeth Collins.

  • Lyric Cook-Morrisey

    Ten-year-old Lyric Cook-Morrisey

  • Dan Morrissey leans on a tree near Meyers Lake where his daughter Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Elizabeth Collins And Lyric Cook-Morrisey

    Elizabeth is described as a white female, 4'1" tall, 65 lbs., with sandy hair and blue eyes. Lyric is also a white female, 4'11" tall, 145 lbs. with brown hair and blue eyes. Anyone with information on the girl's whereabouts is asked to call the Tip Line at (319) 232-8862. According to the Waterloo Courier, a reward for the safe return of the children is available.

  • Black Hawk County chief deputy Captain Rick Abben speaks during a news conference about the investigation of missing children Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, who disappeared last Friday at Meyers Lake, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Law enforcement authorities collect possible evidence near Meyers Lake where Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Law enforcement authorities collect possible evidence near Meyers Lake where Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Misty and Dan Morrissey walk to speak to the media near Meyers Lake where their daughter Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Law enforcement authorities look for possible evidence at Meyers Lake where Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Law enforcement authorities in kayaks search Meyers Lake where Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Local residents sit on a park bench near Meyers Lake where Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, on Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Sarah Staebell ties pink ribbons for Lyric Cook- Morrisse, 10, and Elizabeth Collins,8, missing from Evansdale since last Friday, on light poles along Lafayette Street in Evandale Monday, July 16, 2012. The two girls have been missing since leaving their grandmotherÂ's house Friday afternoon in Evansdale. Their bikes were found Friday afternoon near a bike trail at the edge of Meyers Lake in Evansdale. (AP Photo/Waterloo Courier, Brandon Pollock)

  • An off-duty Cedar Rapids police officer searches the underbrush for clues to the disappearance of Lyric Cook-Morrissey and Elizabeth Collins along the bike trail around Meyers Lake in Evansdale Monday, July 16, 2012. The two girls have been missing since leaving their grandmotherÂ's house Friday afternoon in Evansdale. Their bikes were found Friday afternoon near a bike trail at the edge of Meyers Lake in Evansdale. (AP Photo/Waterloo Courier, Brandon Pollock)

  • This undated photo provided by Black Hawk County police shows 10-year-old Lyric Cook-Morrissey who, along with her 8-year-old cousin Elizabeth Collins, has been missing since Friday afternoon, July 13, 2012. The girls were last scene Friday afternoon leaving their grandmother's house. (AP Photo/Black Hawk County Police via Waterloo Courier)

  • Elizabeth Collins

    This undated photo provided by Black Hawk County police shows 8-year-old Elizabeth Collins, who, along with her10-year-old cousin Lyric Cook-Morrissey, has been missing since Friday afternoon, July 13, 2012. The girls were last seen Friday afternoon leaving their grandmother's house. (AP Photo/Black Hawk County Police via Waterloo Courier)