Investigators searching for two missing Iowa cousins say they want to interview a person who was paddleboating on a lake near where they disappeared 10 days ago.
FBI spokeswoman Sandy Breault said Monday that investigators want to interview the person who was boating July 13 on Meyers Lake because that person may have information that could help the search for 10-year-old Lyric Cook-Morrissey and 8-year-old Elizabeth Collins.
Breault said the boater is not a suspect but that investigators "really do need to talk with the person." The boater has not voluntarily come forward to speak with investigators, who for days have urged the public to step forward to tell what they know. The girls' bikes were found near the lake.
Breault said investigators still believe the two girls are alive.
Law enforcement officials will likely expand their search for the children now that their disappearance is considered an abduction case, experts said.
But experts said it's hard to tell exactly what's going on because officials probably aren't disclosing everything they know, including why they are confident the girls are alive.
Breault said Sunday that investigators want to talk to anyone who was at Meyers Lake in the northeast Iowa town of Evansdale before 3 p.m. July 13.
Breault's plea for help fits with what David Finkelhor, director of the Crimes Against Children Research Center, expected would happen after the case was reclassified as an abduction. He said investigators now may be more dependent on tips from the public.
"They've got to cast a much wider net. They could be miles from that spot there," said Finkelhor, who is based at the University of New Hampshire.
Finkelhor said if the girls were abducted by a stranger, the statistics are grim -- his research shows that 40-50 percent of children in that situation aren't recovered alive. But, he said, abductions by strangers are so rare that it's difficult to predict what might happen.
Several "persons of interest" have been interviewed in the case, and numerous tips from the public have come into investigators. Breault also said that most of the girls' family members have been cooperating with investigators.
Lyric's father, Daniel Morrissey, is being watched closely by authorities but has not been named a suspect. Morrissey, 36, has a lengthy criminal history and is no longer cooperating with police. He has been placed in a pretrial supervision program in two separate drug cases, so parole officers are monitoring Morrissey's actions.
Misty Cook-Morrissey, 34, also has a criminal record. She was convicted of federal drug charges and state theft and alcohol violations. She is currently on supervised release.
She agreed to submit to a second polygraph test Monday to show she is again cooperating with investigators, their aunt said.
Misty was going through the so-called lie-detector test Monday with state and federal detectives at an elementray school in Evansdale, her sister Tammy Brousseau said.
She had submitted to polygraph last week, but had announced she wou ld not take anym ore after complaining she had been harshly interrogated and accused of involvement in the disappearance. That stance caused some friction among family members, Brousseau said, and in recent days investigators repeatedly called the lack of cooperation a distraction for their search.
"Because Mistyu did not want to do the second polygraph test at the advice of her attorney, because she didn't want to be coerced and cornered and told that she did this, there was a little bit of separation. Some of the family felt, 'OK, she's not cooperationg 100 percent.' I hope that turns around now," Brousseau said.
"She's doing it to show that she is cooperating 100 percent so that we can put to rest the idea that there is a family member not cooperating," she added in a phone interview.
Investigators spent much of last week searching Meyers Lake and the surrounding area, which is about 120 miles northeast of Des Moines. The lake was mostly drained and the FBI used sonar technology and divers to search it, so investigators could ensure that the girls were not there.
Breault said investigators believe even the smallest details could be crucial in this case, so she encouraged anyone who had been at the lake, located near Interstate 380, to call -- even if they didn't see the girls.
"Don't assume we know what you know," she said.
Breault said no arrests had been made as of Sunday, but she declined to comment on details of the investigation.
A director at the National Center for Missing and Exploited Children said it is incorrect to assume that the lake search was the focus of the investigation just because it was the most visible.
"There were a lot of other things, I assure you, going on simultaneous to that lake, but law enforcement was right to eliminate that as a possibility," said Robert Lowery, the executive director of the group's missing children's division.
The group has been helping with the search for the Iowa cousins, so he couldn't comment directly on details of the case. But he said the fact that investigators actually drained most of Meyers Lake shows how serious they are about investigating every lead.
Lowery said there's reason to be optimistic, pointing to cases where missing children were found long after they disappeared, such as Elizabeth Smart and Jaycee Dugard.
"We can't lose hope," Lowery said. "There have been many instances where children have been gone hours, days, weeks, months and even years. And we found the children and returned them to their families."
Smart was kidnapped at knifepoint in 2002 in Utah by a handyman who knew her family. Motorists spotted her as she walked with her captors nine months later.
Dugard was taken off a South Lake Tahoe, Calif., street in June 1991 while walking to a school bus stop and was held captive in a backyard compound for 18 years. She was discovered in August 2009 when authorities said her captor took her and her children to a meeting with his parole officer.
The Associated Press contributed to this report.