Kansas City, Missouri (CNN) -- Deborah Bradley appeared calm and joyful just hours before her baby daughter was reported missing, according to a supermarket clerk who sold her baby wipes, baby food and boxed wine.





"She had a smile on her face, like she always does when she comes in here," said clerk Rebecca Guerrero, whom FBI agents interviewed Saturday about conversations she'd had with Bradley.





Surveillance video recorded at a grocery store on October 3 shows Bradley and a man purchasing the items from Guerrero the day before 11-month-old Lisa Irwin was reported missing.





Police, who were joined in their search effort by federal authorities last week, have said they have no suspects or solid leads in Lisa's disappearance.





In an exclusive interview with CNN, Guerrero described the FBI agents' questions.





"They pretty much asked me if she was depressed, ... how she acted around the baby, if she seemed stressed out," Guerrero said. "I told them she never looked depressed around me. You know, she always seemed to have a smile on her face when her kids were around."





Bradley and the girl's father, Jeremy Irwin, are friendly people who were thrilled to have a baby daughter, Guerrero said.





"When they're here, they're happy. They're smiling. They love their kids," she said.





After two years chatting with Bradley in the checkout line at Festival Foods in Kansas City, Missouri, Guerrero said she had learned a lot about the family.





"We would just pretty much talk about what they've been doing, stuff like that; the children, her two sons, and then when she found out she was pregnant with Lisa, that's all we talked about," Guerrero said.





The supermarket clerk said she also told FBI agents Lisa's parents never mentioned anyone wanting to harm them.





"From my interaction (with the parents), I really don't think that they have anything to do with this," she told CNN.





Authorities had expressed frustration recently after Lisa's parents had stopped cooperating with investigators, police Capt. Steve Young said. However, a family spokeswoman for Bradley and father Jeremy Irwin attributed the frustration to "miscommunication," and a subsequent meeting with the parents was held Saturday.





On Tuesday, Irwin's family announced they had brought in a prominent private investigator to help with the search -- a high-profile twist in a case that has gripped national headlines.





Flanked by family members wearing T-shirts with a picture of Lisa and the word "Kidnapped" above it, investigator Bill Stanton said Tuesday night that he wants a "happy ending" to the case.





He told CNN a family friend was paying for his services.





"I will be asking questions," he added. "I am here to seek the truth."





Stanton is a former New York City police officer who has served as a security consultant for several television networks. He said his role is to help "coordinate and focus the family" in both the investigation and in its dealings with the media.





"We are here to cooperate with anyone and everyone that will help us find the guilty party and return Lisa home safely," he said.





Stanton said the family, which remains united and strong despite the "tremendous hardship," will release more information soon. He did not elaborate.





"I know everybody's watching this family and watching this house, and that's fair," he said. "Keep one eye on them, but also keep the other eye out on the streets, in every place. Because there is a bad guy out there, or bad people, with this child. And we want to get this child home safe and sound."





Lisa was last seen around 10:30 p.m. October 3, asleep in her crib, police said. Authorities were called to the home about 4 a.m. October 4.





She turned 11 months old Tuesday, the eighth day of the search.





On Tuesday, authorities focused on
When was she last seen? In which location was Lisa last seen on October 3? what does Bill Stanton want? according to a supermarket clerk what did the mom never seem What is the name of the Investigator? What did the clerk say about her mom? when was the missing child last seen What did Stanton say?
10:30 p.m. October 3, asleep in her crib, a "happy ending" to the case. looked depressed Bill Stanton face, like she always does when she comes in here," 10:30 p.m. October 3, he wants a "happy ending" to the case.
question: When was she last seen?, answer: 10:30 p.m. October 3, | question: In which location was Lisa last seen on October 3?, answer: asleep in her crib, | question: what does Bill Stanton want?, answer: a "happy ending" to the case. | question: according to a supermarket clerk what did the mom never seem, answer: looked depressed | question: What is the name of the Investigator?, answer: Bill Stanton | question: What did the clerk say about her mom?, answer: face, like she always does when she comes in here," | question: when was the missing child last seen, answer: 10:30 p.m. October 3, | question: What did Stanton say?, answer: he wants a "happy ending" to the case.