Evansdale police and Black Hawk County deputies continued their fourth day of searching Monday for two missing cousin in northern Iowa.
About 400 volunteers helped search the area around Meyers Lake in Evansdale, Iowa on Sunday for 8-year-old Elizabeth Collins and 10-year-old Lyric Cook-Morrissey.
The girls were last seen riding bikes around noon Friday. Four hours later, someone found their bikes near the lake along with a purse and cell phone belonging to the younger girl.
The girls' grandmother called police after they never came home.
"Whoever has 'em, just turn 'em in, let 'em loose anywhere so they can call me," Wylma Cooks aid. "Lyric knows my cell phone, she knows my house phone."
Divers have been called in to help search teams that have been dredging Meyers Lake. Police are talking with family and friends to gather more information, and officers have also been interviewing registered sex offenders who live in the area.
"Today I'm feeling pretty good," Misty Cook-Morrissey said Sunday. "Sometimes, when you think about it, you wonder if they're dead somewhere, but you try to push those thoughts out of your mind."
Cook-Morrissey said her 10-year-old daughter Lyric might have tried to swim at the lake, despite a swimming ban. She said the family swims at another nearby lake regularly, and described Lyric as a good swimmer.
Elizabeth's mother, Heather Collins, said it's rare for her daughter to venture too far from home, but she may have been persuaded by her older cousin.
"We've talked about that before," Collins said "We've told them they're too young to go far."
Police are still calling it a missing persons case, but investigators have not ruled out foul play. And one question that frequently comes up in cases like this: why isn't there an Amber Alert?
"Because we have no person that was seen and we have no vehicle that was described, so we can't issue an Amber Alert by their guidelines," said Black Hawk County sheriff's Capt. Rick Abben.
An anonymous person has offered a $5,000 reward. A few tips have come in, but none have panned out.
Information from the The Associated Press was used in this report