KANSAS CITY, Mo. — Kansas City authorities searched a cistern at a vacant house Tuesday but came up empty again in their hunt for a missing 10-month-old girl.
Local firefighters took turns being lowered into the cistern, a receptacle designed to hold rainwater and other liquid, beneath a backyard deck at a home neighbors said had been empty for about four years. Afterward, police said they still had no clues and no suspects in Lisa Irwin's disappearance.
Lisa's parents reported her missing after her father returned home from work around 4 a.m. last Tuesday. Her parents said someone must have crept into their home while the child's mother and brothers slept and snatched the girl.
The search of the property came a day after a court ordered Kansas City television stations to submit all footage of interviews with the girl's family and friends.
Bradley has said police told her last week she failed a lie detector test. She has denied having anything to do with her daughter's disappearance.
Grand jury subpoenas from Clay County Circuit Court were sent late Monday to at least four network affiliates in Kansas City, according to their websites. The subpoenas asked the television stations to submit "all footage, including raw footage of any interviews or statements given by neighbors, family or friends of the family, regarding missing baby, Lisa Irwin."
Video: Missing baby Lisa: What are police doing? (on this page)
The subpoenas, which were requested by the Clay County prosecutor's office, said at least two of the stations were told to appear with the footage in court on Oct. 18.
Jim Roberts, a spokesman for the prosecutor's office, said the subpoenas were needed to prevent broadcasters from destroying video they might otherwise discard because it could be needed later. The subpoenas were issued by a sitting grand jury, not on called specifically for this case.
Detectives and crime scene investigators were at the family's home Monday for more than two hours scouring areas of the backyard and poking through shrubbery and grass in the back of the house and in neighbors' yards. Police earlier in the investigation searched a landfill, nearby woods, an industrial park and sewers in their effort to follow up on more than 300 tips.
"Our detectives are doing everything possible you would expect them to do in this case," said Capt. Steve Young, spokesman for the Kansas City Police Department. He declined to comment on the subpoenas.
Bryan McGruder, vice president for news at WDAF, said the station would provide all footage it had aired about the case. But he said the station would not hand over any raw footage because workers "routinely recycle what we use."
R. Michael Cassidy, a professor at Boston College Law School, said there could be several reasons for seeking the footage. He said investigators may want the footage to find inconsistencies in parents' accounts of the events surrounding their daughter's disappearance.
"It could mean that they have one or both of the parents as suspects, and they are developing evidence of everything they said in the past and prior to the arrest," Cassidy said Tuesday. "To show that someone's story has shifted over time can also be very damning."
Police may also want the footage to review "the landscape around the house," shortly after the disappearance was reported.
"It could be that these visuals of the immediate area are important," Cassidy said.
Bradley, the mother, is preparing to be arrested, the baby's aunt said earlier Tuesday.
"It's what the police do," Ashley Irwin told ABC's "Good Morning America." "They don't have any leads so they just have to pin it on somebody."
But police refuted that an arrest was imminent, telling The Kansas City Star it "was absolutely not true."
“We don’t feel any pressure to accuse anybody,” Young said. “We are under pressure to do what we can to find a child.”
Ashley Irwin told ABC she didn't believe her sister-in-law could have anything to do with Lisa's disappearance.Video: Missing baby’s parents: ‘We just need her back‘
"She doesn't care what people say about her, she doesn't care what people think about her, all she cares about it getting Lisa home," Ashley said. "She's genuine; she loves that child. It's her baby … she would never do anything to hurt her."
Last Thursday, Bradley pleaded for her daughter's safe return on NBC's TODAY Show .
“Please bring her home,’’ she said tearfully. “Drop her off anywhere safe — the fire department, a church, a police station. Bring her somewhere safe, no questions asked. We just want our daughter back. We’ll do anything to get her.’’
The Associated Press, NBC News and msnbc.com staff contributed to this report.