Black Hawk County Sheriff Tony Thompson said investigators would be deliberate in pursuing the case of Lyric Cook and Elizabeth Collins, who were 10 and 8 when they disappeared in Evansdale in July. Hunters stumbled upon two bodies believed to be Cook and Collins in a wooded wildlife area some 25 miles away on Wednesday.
Thompson said it could take "several weeks" for their autopsies to be complete and the results to be made public.
"We're going to be extremely meticulous and we're not going to apologize for that," he said a phone interview with The Associated Press. "We've got an opportunity to find a killer."
After nearly five months of chasing tips and theories about the girls' whereabouts, Thompson said police "finally have something credible. We finally have something we can sink our teeth into" in the high-profile case.
Thompson's remarks indicate the case is becoming a homicide investigation. At a news conference Thursday, Thompson's chief deputy said the investigation was leaning that way but that police would wait for the autopsy results before making the change.
Teams of local and federal officers have scoured the Seven Bridges Wildlife Area in Bremer County for evidence since the discovery of the bodies, searching in ditches along the road, fields and woods. The Iowa Medical Examiner's Office, which is handling the autopsies, was also at the scene. That office has declined comment on the autopsies.
The sheriff's office had asked neighboring counties, including Bremer County, to search their parks and wildlife areas for the girls after they vanished last summer, Thompson said. He said that as far as he knows, Bremer County officers did search the popular hunting and fishing spot but that the bodies would have been hard for anyone to spot.
"Even the hunters, if they had gone five feet in either direction, would not have found those bodies," he said.
The girls left the Collins' home in Evansdale, where they were being watched by their grandmother, for a bike ride July 13 and never returned. Authorities found their bikes and a purse near a recreational lake in the city, and their disappearance sparked a massive search and kidnapping investigation involving the FBI, state and local police.
The cousins' families had been hoping they would come home, maybe even for Christmas, until this week's news.
"This 100 percent blindsided us and it absolutely did them as well," said Sara Curl, a friend of the girls' families.
Curl helped organize a vigil for the girls Thursday night, one of many community activities that will be needed to help people heal in the days ahead, she said. The vigil was held around a Christmas tree that had been set up to honor the girls - with the hope they would be home for Christmas to see it.
In a posting on her Facebook page Thursday, Heather Collins, Elizabeth's mother, said it was not the outcome the family wanted but now "we know our girls are dancing up with our savior." Collins thanked the community for an outpouring of support.
When Zuhra Hodzic, 25, of Waterloo, saw that Facebook message, she was heartbroken. Hodzic was a volunteer on searches for the girls and other community activities.
"You're left with a blank," she said searching for the words and fighting back tears. "It's heartbreaking. It's devastating."
For her and many others at the vigil, the focus turns now to finding who is responsible.
"Our community deserves justice, and I hope our FBI agents and cops and everybody involved gets for us what we deserve," she said, "and that's justice for the whole family and all of us."
(Copyright 2012 by The Associated Press. All Rights Reserved.)