ABC News Viewers Pitch In on Stolen Baby Mystery

PHOTO: paul joseph fronczak, missing person, babyPlayFamily Handout
WATCH Who Is Paul Fronczak? Age-Progress Image Could Yield Clues

Hundreds of ABC News viewers wrote in and many offered tips that could help solve the decades-old mystery of stolen baby Paul Fronczak after the case was featured in an exclusive ABC News "20/20" report Friday.

The "20/20" investigation, which was led by ABC News' Barbara Walters and Chief Investigative Correspondent Brian Ross, told the story of the now 49-year-old Nevada man who recently discovered he had been living his whole life with parents who, unbeknownst to him, were not his biological parents.

In 1964 baby Paul Fronczak was stolen from a Chicago hospital. More than a year later, an abandoned child of the right age was discovered in New Jersey, and the Fronczaks believed the baby was theirs. The Fronczaks took the boy home, and the missing baby case was closed in 1966.

But nearly half a century later, DNA testing revealed the man who calls himself Paul Fronczak is not related to the family with whom he grew up.

For the last few months, ABC News "20/20" followed the man raised as Paul Fronczak on his mission to solve the two mysteries in his life: who he really is and what happened to the real Paul Fronczak.

WATCH: Stolen at Birth, a '20/20' Investigation

In the days following the "20/20" report, which aired last Friday, many viewers have come forward with what they believe are possible answers to those questions. ABC News has already begun to follow up on these tips, while at the same time, the FBI, which recently re-opened the case, says it is working "solid new leads."

"We believe there's someone out there that has information," Bob Shields, the special agent in charge of the Chicago FBI office, told ABC News last week. "We hope to get that one lead, that one tip that'll come in to provide us that information."

ABC NEWS TIP LINE: Who Is Paul Fronczak?

Among the comments from viewers were some that the man raised on Paul Fronczak resembles them or someone they know.

"I had a teammate who looked very, very much like Mr. Fronczak while I played Army baseball in Germany," wrote one viewer from Worcester, Mass.

Others wrote in with suggestions about where the stolen baby Paul Fronczak is today. One viewer said she believes the stolen baby grew up to be a Missouri man who is looking for his real family.

"I wonder if he is the Paul that was taken from the hospital," she wrote. "I looked up his work address since he had no email and I left him a message with this information about the circumstances of the 1964 case."

Another individual, who said he grew up in Chicago, said he saw a personal likeness to the age-progression drawings commissioned by ABC News of what the real baby Paul Fronczak could look like.

"I just got done watching this episode about the missing baby after a friend of mine told me that the progressive composite picture that was aired looked like me, so I looked for the episode and watched it," he wrote. "I do have to say the picture does look somewhat like me and I too found out that I was adopted with no answers as to whom my biological parents are."

And some viewers from Chicago wrote in to say they may have seen the woman who dressed as a nurse to steal the real baby Paul Fronczak from Chicago's Michael Reese Hospital in 1964.

But investigators still need your help. If you have any information about the Fronczak case, you can send your tips to ABC News, or find information on sending your clue directly to the FBI, by CLICKING HERE.