Agents and Kansas City police spent about two hours Friday at the Deffenbaugh Industries landfill in the suburb of Shawnee, FBI spokeswoman Bridget Patton said. She wouldn't discuss details but confirmed the activity was related to the search for Lisa Irwin, whose parents said was snatched from her crib in the middle of the night.Patton said it was the second time the FBI had been at the landfill, which investigators also searched Tuesday - the same day the baby was reported missing - and it wasn't uncommon to search an area several times. Police said agents also went back to the family's home and used metal detectors to search the yard. Lisa's mother, Deborah Bradley, said in an interview with The Associated Press earlier Thursday that police told her she failed a lie detector test and accused her of being involved in her baby's disappearance. Bradley said police never showed her the test results and she denied knowing anything about what happened to her daughter. She and Lisa's father, Jeremy Irwin, said their daughter was abducted sometime late Monday night or early Tuesday morning. "They said I failed (a polygraph test)," Bradley, 25, said. "And I continued to say that's not possible because I don't know where she's at and I did not do this." Irwin, 28, said he also offered to take a test but police told him it wasn't necessary. Kansas City police spokesman Steve Young declined to comment on whether the parents have been tested, citing the ongoing investigation. The couple said police have treated them like suspects and that Bradley in particular has been preparing for the possibility of charges. She said detectives told her: "`You did it. You did it. And we have nothing."' Experts said the frustration is understandable but that police often focus on close relatives in such cases, in part because statistics show that far more infants and young children are killed by a parent than a stranger. "Suspicion almost always falls heavily on the parents, especially when it's young kids," said David Finkelhor, director of the Crimes Against Children Research Center based at the University of New Hampshire. "For a parent who has been a victim of a true stranger abduction, this is devastating. You're dealing with the loss of a child, and police are considering you as one of the prime suspects," Finkelhor said. "You can get non-cooperative because the family is feeling mistreated by police." Police said Lisa's parents decided to stop cooperating with investigators late Thursday, but the couple released a statement saying they never stopped and reiterated Friday their focus was "to bring Lisa home." Bradley and Irwin, both dressed in jeans and sweatshirts, held hands and appeared close to tears several times during their 20-minute interview with AP. "We need her. We have to have her. She's our link that ties everybody together," Irwin said. Irwin, an electrician, said he returned from work around 4 a.m. Tuesday and discovered Lisa was missing. Bradley said she last checked on her daughter around 10:30 p.m., then fell asleep in her bed with her 6-year-old son and a stray kitten they found earlier in the day. The parents said they frantically searched for Lisa but found only their front door unlocked, a window open and house lights blazing, lending credence to the theory that the baby may have been snatched by an intruder. They also said the family's three cellphones were missing, though police said that information provided no leads. "The main problem I think that we're facing is that everybody (else) has an alibi," Irwin said. "I was at work. I've been cleared. All these other people we were worried about ... the FBI said they've been cleared. The only one you can't clear is the mother that's at home when it happens `cause there's nobody else there." Bradley said she understood why investigators would be looking closely at the family, especially her. "You see stuff like this everywhere. You watch the TV, and there's some crazy person doing something insane. There's been too many times stuff has happened," she said. "They have to assume what's worst ... but it felt like it was taken really, really far." Ernie Allen, president of the National Center for Missing and Exploited Children, noted that most infants abducted by a stranger usually are eventually found alive but said investigators' seemed to be taking a normal approach as they search for Lisa. "Part of what we train law enforcement chief executives around the country to do - it doesn't seem fair in a moment of crisis - you polygraph, interview and identify those closest to the child," Allen said. "You work a variety of scenarios and continue to pursue them until you can rule them out." ---
Associated Press writers Bill Draper and Heather Hollingsworth contributed to this report from Kansas City, Mo.