Iowa mom thinks missing girls may have been 'taken' Mother says the girls don't go to or swim in Meyers Lake Authorities are draining the lake, near the spot where the girls' bikes were found Scent dogs ran around the lake and stopped at the water's edge (CNN) -- The mother of a missing Iowa girl says she thinks there is a chance she and her cousin were snatched and are not at the bottom of a lake. "Because we haven't found them anywhere in the surrounding area, I feel like maybe they were taken," Misty Cook-Morrissey, mother of 10-year-old Lyric Cook, told CNN on Wednesday. Lyric and 8-year-old Elizabeth Collins were last seen by their grandmother on Friday when they left to go on a bike ride. Scent dogs used by searchers looking for signs of the girls ran around Meyers Lake and stopped at the water's edge, Cook-Morrissey said. Authorities were draining the lake, located near an area where the girls' bicycles and a purse were found hours after they were reported missing. They don't go there. They don't swim there. My daughter is familiar with swimming in lakes so I don't think she would be scared of this lake, but they don't come here and swim here. Cook-Morrissey said she'd be "more comfortable" in the theory that the girls might have been abducted "once they drain the lake and we find nothing there." "If you've taken our kids," she said on national TV, "bring them back." The FBI brought two dogs to the area to search Monday night, and the dogs were used again on Tuesday, FBI spokeswoman Sandy Breault said. The dogs used scent pad samples taken from the girls' shoes and picked up a scent trail, but Breault said she couldn't say what, if anything, it led investigators to. Authorities said Tuesday that they didn't know whether the girls had been at the lake. "We have their bicycles and we have the purse, and that doesn't tell me that they've been there, just that those items are there," said Rick Abben, chief deputy for the Black Hawk County Sheriff's Office, It could take two to three days to drain the lake to a point where searchers will know if anyone is there, Evansdale Mayor Chad Deutsch said. The lake covers approximately 25 acres. When Deutsch heard that two little girls were missing in his town, the first thing he did, he said, was to make sure every city asset that was needed was made available to the county sheriff. We're bracing for the worst but hoping for the best. Calls are coming in to a tip line, Abben said, and each bit of information is being checked out. Lyric's grandmother, Wylma Cook, said she doesn't believe the girls intended to go swimming. "I don't think they would have even known the way to Meyers Lake," she told HLN's Nancy Grace on Tuesday. Relatives say they have been cooperating with police. Heather Collins, Elizabeth's mother, told HLN's Jane Velez-Mitchell that if the girls, in fact, were abducted, she would not pass judgment. "We just want our children brought back," she said.