The investigation into the disappearance of Paul Joseph Fronczak, who disappeared from a Chicago hospital as a newborn in 1964, is active again in light of new evidence. The original case files will be reopened in hopes that Fronczak will learn his real identity.

An investigation into a stolen baby has been re-opened after DNA evidence showed someone else's child was returned to the missing infant’s parents nearly 50 years ago.

The FBI told Chicago newspapers that they were re-investigating the case of Paul Fronczak, who was taken as a newborn from the city’s Michael Reese Hospital in 1964.

A year later, federal investigators became convinced that a toddler found abandoned in Newark, New Jersey, was Paul and the child was given to Chester and Dora Fronczak, who raised him as their own.

The identification was based in part on the shape of the child’s ear, The Chicago Sun-Times reported.

However, the man named Paul Fronczak, now 49 and living in Nevada, revealed earlier this year that a DNA test had showed he was not their biological son, the paper said.

He has now been trying to find out who he actually is and what happened to the real Paul Fronczak.

“I am very happy to see the FBI reopen the case, thanks to my ruffling the media’s feathers!” he said in an email to the Sun-Times Wednesday.

“I feel I am one step closer to solving these two tragic mysteries, and one step closer to a very happy ending!”

A Facebook page called “Who is Paul Fronczak?” says “Imagine waking up one day to find out that the identity you've had your entire life isn't true, that the family who raised you isn't really your family at all, and that you don't even know your real name.”

In a video posted on the page, Fronczak read an email he sent to his parents -- addressing them as “dear mom and dad” -- in which he revealed the DNA tests had showed he was not their biological son.

Facebook.com/WhoIsPaulFronczak A Facebook page has been set up to try to discover the fate of Paul Fronczak, a baby stolen in 1964, and the real identity of the child given to his parents in 1965 in the mistaken belief it was their son.

“First, I am your son and always will be,” he said.

But Fronczak said he did not “really know who I am” and that the real Fronczak “might still be out there.”

“I know this is hard for you,” he said. “I love you both and you have been wonderful parents. I am not doing this to hurt you … this is just about finding the truth.”

Fronczak told the Chicago Tribune that his parents supported his attempts to find his true identity.

“I’m in this for the long haul. I’m not going to quit,” he said. “I think that the perfect ending would be to find the real Paul, see that he’s doing well and then on the same day find my real family. It would also be nice to have an actual birth date that I could believe in.”

Joan Hyde, a spokeswoman for the FBI office in Chicago, confirmed to the Sun-Times and the Tribune that the case had been re-opened.

She told the Tribune that they had had a “lucky break” when they discovered the original files on the case.

“It was deemed appropriate to take a fresh look at the evidence that we have and possibly re-interview sources that are still around,” she added.

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