By ANGELA M. HILL

On the 50th anniversary of an unsolved mystery that continues to draw attention and leads from around the world, Paul Fronczak is still hoping to uncover his true identity and find the baby that was stolen a half century ago from the woman he believed was his biological mother.

"I feel super hopeful that we're going to solve both these mysteries this year," Fronczak told ABC News.

Fifty years ago Sunday, baby Paul Fronczak was stolen from his mother's arms in a Chicago hospital the day after his birth. A woman posing as a nurse came into Dora Fronczak's room and claimed the doctor wanted to see the baby. The abduction launched a nationwide search for the child and his kidnapper. Just over a year later, a toddler of the right age was discovered abandoned in Newark, N.J. and the FBI believed they had closed the case, at least as far as the missing baby went. The parents, Dora and Chester Fronczak, happily took the child in, believing it was theirs, and raised him as their own.

But last year, the then-49-year-old man raised as Paul Fronczak took a DNA test to find that he was not, in fact, the Fronczak's biological child. Since then, he's been on a mission to solve two mysteries in his life: Who he is and what happened to the real Paul Fronczak?

Do you have a tip that could help solve the mystery? CLICK HERE to send it in to ABC News.

His search has generated such widespread attention that the FBI reopened the cold case and assigned a dedicated task force to the investigation. The FBI won't go into details about their findings, but say the investigation is ongoing.

"We continue to pursue leads as information comes to us, and once again, we appreciate the publicity and any new leads it might generate," said Joan Hyde, spokeswoman for the Chicago FBI office.

"I really feel someone knows something and it's about time they spilled their guts," Paul Fronczak said.

Baby Paul Fronczak, left, was stolen from the hospital as a newborn. An age-progressed artist rendering, produced by Phojoe.com, right, shows what he could look like today. Credit: Family handout | ABC News

With the help of ABC News' "20/20," Fronczak has dedicated the past year to solving both mysteries. Following the initial "20/20? report on the Fronczak mystery in November, ABC News received hundreds of new clues from around the world to its tip line and website.

One of the tips read, "The baby was stolen by a lady known as the 'welfare queen'. She had many, many, schemes to get money and would have most likely sold the baby."

The woman referenced in the tip was Linda Taylor, a notorious figure in Chicago in the 1970s and '80s. She was dubbed America's "welfare queen" and vilified by President Ronald Reagan. In a televised speech, Reagan said a state government committee accused Taylor of a wide array of crimes and said the committee discovered she used up to 100 aliases and 50 false addresses.

Taylor's son, 64-year-old Johnnie Harbaugh who lives in a Chicago suburb, sat down with ABC News to talk about his mother and her possible role in the Fronczak mystery.

"My mother was capable of anything. Not only stealing a baby, but she could steal you," Harbaugh said in the ABC News interview. "She was just that kind of woman. You know, she done whatever it took for her to survive."

READ: Son Suspects 'Welfare Queen' May Have Stolen Baby Paul Fronczak

After looking at the hospital's baby picture of Fronczak, Harbaugh claimed that not only did he recognize the baby, but said he used to play with the child when he was a teenager living with his mother. Harbaugh said the baby had just showed up one day.

"You know what? He had a name. But we called him Tiger," Harbaugh said.

Taylor, Harbaugh said, was a master of disguise and could pass for white, black, Puerto Rican or Hawaiian in her schemes to collect fraudulent welfare payments. Sometimes she even posed as a doctor or nurse, he said.

"She had a room with nothing but wigs and nurse dresses and shoes," Harbaugh said.

In the 1970s, when Linda Taylor was put on trial for welfare fraud, she actually came under investigation for stealing the Fronczak baby. A local newspaper reported that one of her ex-husbands said that one day in the mid-1960s Taylor appeared with a newborn baby, even though she was not pregnant.

Harbaugh said he didn't say anything to the authorities about the sudden appearance of the baby because he was in trouble with the law back then. He hadn't told his story until he spoke with ABC News and a reporter from Slate.com in recent months.

Harbaugh said the baby disappeared as suddenly as it had appeared. One day he came home from school and the child was gone. Harbaugh said he's "positive" it was taken by one of Taylor's boyfriends to Tennessee.

Taylor died twelve years ago, but the FBI told ABC News they are looking back at Taylor's possible involvement with fresh eyes. Hyde, the FBI spokeswoman, admitted old cases like this one present unique challenges due to the passage of time, but they remain hopeful.

"We have newer technology and tests that we can apply to any physical evidence, now as opposed to 50 years ago," said Hyde.

Fronczak said his search for the truth is a part of his daily routine and he won't stop.

"It's the last thing I do at night and the first thing I do in the morning," he said. "If you don't stay on top of it you might miss the one clue that can solve it. And I'm not going to be that guy that misses that one clue."