Where's Baby Sabrina?

Troy Roberts Reports On One Family's Search For Their Daughter

(CBS)  With permission from the Aisenbergs, the FBI tapped their phone so that any call from a kidnapper could be traced. One of the first calls was from Steve’s brother, Dave, a lawyer, who warned Steve to be wary of the police.

When detectives listened in, they were amazed that Steve, supposedly awaiting a call from his child’s kidnappers, never answers the call-waiting beep that kicks in -- not once, but twice

To the police, this was proof that the Aisenbergs knew much more about their baby’s disappearance than they were saying. Any other concerned parent would have cleared that line immediately. Suspicious, they confronted Marlene, who said they told her they believed she knew where Sabrina was – or what had happened to her. "We called them here to help us find her, or who took her," says Marlene. "Where is she?"

Twenty-four hours after Sabrina was reported missing, the Aisenbergs were frustrated with the police response. They say police ignored tips about possible Sabrina sightings.

"They tried to find a body," says Marlene.

"The investigators never really got past Mr. and Mrs. Aisenberg," says Graham Brink, a reporter for the St. Petersburg Times. He's written extensively about the case. "In their minds, they could never rule them out as prime suspects."

"Don't investigate us at the exclusion of looking for our baby," says Steve.

Before Sabrina disappeared, life for the Aisenbergs largely revolved around their three children: Sabrina and her two older siblings, William, then 9, and Monica, then 5.

Marlene even started her own business for kids, running a baby and toddler exercise program. Steve worked real estate in Tampa’s booming economy.

But ugly gossip was spreading. Meanwhile, the Aisenbergs continued to cooperate with the investigation. Sheriff's detectives gave the Aisenbergs lie detector tests and then leaked information that some of Marlene's answers were "deceptive," even though Marlene says both tests were inconclusive.

The investigation was now three days old, and Steve heeded his brother’s advice. He hired Barry Cohen, one of the most high-profile and combative lawyers in Florida.

Cohen says there is nothing that points to his clients' guilt, but he says detectives had one mission: to prove the Aisenbergs were involved. "When I saw the police were acting in bad faith and that they were destined to try to frame Marlene and Steve, that’s when we stopped cooperating," says Cohen.

The Hillsborough County Sheriff’s Office refused to talk to 48 Hours Mystery about the case, but McGinty says the cops definitely pursued other leads, even though the vast majority were from people who mistakenly thought they had spotted Sabrina.

"We went to their Aisenberg war room, where they had volumes of information, places they’d been to, thousands of different leads," says McGinty.