By BRIAN ROSS, BARBARA WALTERS and ANGELA M. HILL

Sam Miller stood in his Dallas home and stared at a picture of a baby that was stolen from a hospital 50 years ago. The resemblance is uncanny.

"It looks like me," he said looking at the baby photo and then an age-progression image that shows what the child could look like today. "I look like that guy and I have no idea where I came from."

As part of an ABC News "20/20? investigation, Miller was what seemed to be the strongest lead yet in the search to find Paul Fronczak, a baby stolen from his mother's arms a day after his birth in a Chicago hospital in 1964.

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

In November "20/20? aired its first piece on the Fronczak mystery, and the age-progression images used in the report, created for ABC News by Phojo.com, got the attention of a friend of Miller's.

"There she sees this picture up on TV, and she called me. She goes, 'You're going to think I'm out of my mind, but you've got to go to this website and look at this. And so I did, and we all just stood there in shock," Miller told ABC News of seeing the image.

Not only did Miller closely resemble the age-progression image, but at 49 years old he was about the right age and his own baby pictures bore a striking resemblance to the only known picture of the baby Fronczak.

Get Caught Up: Who Is the Real Paul Fronczak?

Miller, now a Microsoft executive, grew up in a suburb outside Chicago but did not learn he was adopted until earlier this year after doctors told him his kidney disease, which he has battled for years, had taken a serious turn for the worse. He called a cousin for information about the family's medical history.

"She started the sentence with, 'What kidney disease? You mean you don't know you're adopted?" he said.

So now for Miller, who has end-stage renal disease, and his wife and two children, the prospect of finding his real family could be a matter of life and death.

"So here I am. And I hope that I'm able to find a kidney, find my family and go on with my life," he said. "Because I'm kind of near the end."

ABC News "20/20? was with Miller when he received a call from a government office in Chicago that held his original adoption papers, which "20/20? helped to get unsealed.

In the 90-second call, Miller learned that the files showed he was not Paul Fronczak.

After the call Miller embraced his family, teary and disappointed. But with more work to do.

"I have a brand new search," he said.

Do you think you can help solve the case of stolen baby Paul Fronczak? You can contact the FBI by emailing Chicago@ic.fbi.gov or by calling 1-800-CALL-FBI, or you can contact ABC News' Barbara Walters and Brian Ross by writing in to the private tip line by CLICKING HERE.