Where's Baby Sabrina?

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

(CBS)  But there's no doubt the police felt stymied, just when they thought they were on the verge of breaking the couple. The police thought their best suspects were sitting at home, so in a highly unusual move, detectives got a warrant allowing them to secretly plant tiny listening devices called bugs in the Aisenberg's kitchen and bedroom.

"I think they thought it was their last chance of getting the Aisenbergs," says Brink. "The investigators didn’t have any physical evidence at that point. They didn’t have any eyewitness statements. They hadn’t found Sabrina. There had been no ransom note."

48 Hours asked Mike Perros, a wiretap and bug detection expert, to come to the Aisenberg home to demonstrate how the wiretapping operation worked. He explained that the sound quality is excellent, as long as it's applied correctly.

Every day, for nearly three months, from 7 a.m. to midnight, sheriff deputies listened and recorded thousands of private conversations going on in the Aisenberg home.

Sabrina had only been gone for two months, but a federal grand jury was convened to examine her disappearance. The Aisenbergs were asked to testify, but Cohen advised them to invoke their Fifth Amendment rights. "I think we did what we felt was necessary at the time," says Steve. "We did what we were advised to do."

Cohen says he advised his clients not to testify because of the reputation of lead federal prosecutor Steven Kunz: "He has no business being in the system."

As the grand jury heard testimony, Social Services workers showed up at the Aisenberg's front door to investigate whether the couple's older children, William and Monica, were being mistreated.

"We were furious," says Marlene. "I think they wanted to scare us and let us think that they were taking away our children."

But it was just the beginning of the Aisenbergs' ordeal.

As in the JonBenet Ramsey case, detectives looking for Sabrina were convinced the parents were somehow involved.

"I think once law enforcement collectively decided that the Aisenbergs were responsible and guilty, then whatever it took to implicate and to charge them, that was going to be done," says John Fitzgibbons, a former U.S. attorney now in private practice in Tampa.

Meanwhile, the Aisenbergs were trying to keep their hopes alive. "What I think about is: 'How can I bring my daughter home?' " says Steve.

By May 1999, the Aisenbergs were struggling financially, so they sold their house in Florida and moved back to Steve’s childhood home in Bethesda, Md.

Just four months later, on Sept. 9, Marlene received some unexpected visitors at home. Frantic, she called Cohen. "They're in the house. They've broken into the house," recalls Marlene. "There's a gun being pointed right at my face. It was the most horrifying thing other than waking up and finding my daughter not in her crib."

The intruders told Marlene they were the FBI. At the same time, agents were arresting Steve across town. He says they put him in a cell, strip-searched him, and took fingerprints and photos.

Marlene and Steve were later released on bail, using Steve's father's home as collateral. The Aisenbergs were indicted for conspiracy and for lying to investigators, not for murder. The charges, if proved, could send them to prison for up to 30 years.