(CNN) -- Despite below-freezing temperatures, divers searched two bodies of water in central Maine on Friday, looking for signs of a toddler last seen more than seven weeks ago.
Authorities said there was no initial indication that Friday's search led to the discovery of anything related to Ayla Reynolds' disappearance. They added that more searches could be forthcoming.
"If we don't find anything that can be attributed to Ayla today, we'll be back again some other day -- maybe someplace else," said Lt. Kevin Adam of the Maine Warden Service.
Ayla's father, Justin DiPietro, told police he put his then-20-month-old daughter to bed at 8 p.m. December 16 in the first-floor bedroom of their Waterville, Maine, home. He called police the next morning, just before 9 a.m., to report her missing.
Police have said the three adults in the home that night told them "someone snuck into the house, went into the bedroom where Ayla was sleeping, and no one heard or saw anything."
Yet authorities said days ago -- and Maine Department of Public Safety spokesman Stephen McCausland reiterated Friday -- that there is no evidence of any break-in or kidnapping.
"We still think they know more than what they've told us," McCausland said Friday. "We have grave doubts that an abduction ever took place there."
No arrests have been made related to Ayla's disappearance, and no one has been identified as a suspect. Nor has there been any public indication of where the girl may be, with McCausland saying authorities are branching out to cover as much area as possible in a hunt for clues.
Friday's search of part of the Kennebec River, near the Carter Memorial Bridge, and Messalonskee Stream, near the North Street bridge, is part of that effort.
Both bodies of water had been looked at before, though Adam noted that the divers returned because "we didn't search them to the amount that we wanted to last time."
He explained that inclement weather prompted divers to twice cancel new searches. Conditions were better Friday, though the area the divers could safely cover was still restricted by daytime temperatures that were below freezing.
"It's not like diving down in the Keys," Adam said, noting that divers are underwater for only about 20 minutes at a time. "It's 20 degrees out there, and the water is freezing. So it just takes time. Plus, it's dark."
Testing on blood found in the basement of Ayla's home determined that some of it belonged to the girl, McCausland said Sunday.
A website created by Ayla's family disclosed the police findings in a posting that same day, saying investigators told them the blood found was "more ... than a small cut would produce."
Earlier Sunday, McCausland said that while some of the blood found "was visible to the naked eye, some wasn't."
DiPietro, Ayla's father, sleeps in the basement of the home, which is owned by his mother. He has said that he would never do anything to harm his daughter.
"I have to believe that Ayla is with somebody, and I just want that person to find the courage to do the right thing and find a way to return her safely," he said in a statement issued soon after the girl was reported missing.
When asked Friday about communication between authorities and Ayla's family, McCausland said, "There has been contact this week, and we hope that contact will continue."
The state spokesman noted authorities have received more than 700 tips, admitting that the pace has slowed down in recent days. The fears of a worst case scenario are increasing, as time passes, he acknowledged.
"It's been 48 days, and our concern grows every day," McCausland said. "But we remain hopeful that we're going to find her."