Lisa Irwin's parents reported her missing early Tuesday after her father returned home from work. Her parents said someone must have crept into their home while the child's mother and brothers slept and snatched the baby girl.
The parents said a front window had been tampered with, and police were seen crawling through one Sunday. An officer was back at the house early Monday for about 10 minutes, walking around to the rear.
He did not speak to the media. Capt. Steve Young, the police spokesman, said only that detectives have been pursuing leads but are "at the mercy of the next good idea."
"We're trying everything we can," Young said. "We're trying every idea that we can."
But although Young said leads are coming in "all the time," investigators have said they have nothing solid so far and no suspects despite an extensive search of the family's quiet neighborhood, including their home and neighbors' houses, a nearby woods, sewers and a Kansas landfill.
John Hamilton, a former Kansas City police officer who's now an associate professor of criminal justice at Park University, said crime scene re-enactments aren't common but can be valuable in some instances.
"When there's a large amount of evidence there ... the re-enactment thing is probably not a necessity," he said. "What it says to me is they were not able to find much physical evidence at the scene."
A re-enactor likely walked through the house holding a doll about the same size and weight as Lisa to see how an abductor might have navigated the home in the middle of the night when everyone was asleep, he said. The goal would be to find small details that might initially have been overlooked or a trigger that could shift the investigation in a whole new direction.
"I like (re-enactments)," Hamilton said. "They are a different kind of think-out-of-the-box way of approaching things."
Lisa's parents, Jeremy Irwin and Deborah Bradley, spoke with detectives late Saturday, Young said. He would not say how long investigators interviewed the couple, but he did say police were pleased the parents were meeting with them. Police said late Thursday that the couple had stopped cooperating, but the family quickly denied the claim, saying they simply needed a break that night from police questioning.
Bradley has said police told her she failed a lie detector test.
Family spokesman Mike Lerette said Monday in text messages to The Associated Press that the family is working closely with police, and that investigators "seem to be following up on a lot those lists we all put together over the week."
He said the family had little information about the investigation.
"We're tracking it just like everyone else though," he said, "by watching the news hoping to hear breaking good news."
Associated Press writer Bill Draper contributed to this report.