Updated

The FBI has reopened its investigation into the 1964 kidnapping of a newborn from a Chicago hospital, after DNA tests revealed that a boy found in New Jersey fourteen months later and returned to the missing baby's parents wasn't actually their son.

Paul Fronczak, 49, is a married father of his own now and works as a college administrator and living in Henderson, Nev. He told the Chicago Sun-Times in June that he had long wondered why he didn't resemble his parents, Chester and Dora Franczak, so they underwent DNA testing earlier this year to see if he was their biological son. He wasn't.

Joan Hyde, a spokeswoman for the FBI's Chicago office, told The Chicago Tribune that investigators decided to reopen the case after locating evidence files from the original 1964 investigation.

"It was deemed appropriate to take a fresh look at the evidence that we have and possibly re-interview sources that are still around," Hyde told the newspaper Wednesday.

Hyde told The Associated Press that the bureau could interview witnesses as part of the investigation, which she said is expected to "take time."

In an interview Wednesday with the Chicago Tribune, Fronczak said that his parents support his desire to discover his identity and find out what happened to his parents' biological child.

"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," he told the newspaper.

Hundreds of police officers and FBI agents searched for the Oak Lawn couple's newborn son after his abduction from Michael Reese Hospital in April 1964. The case came to an apparently happy end more than a year later when an abandoned child resembling the Fronczak's baby was found in New Jersey and returned to them.

A woman who answered the phone Wednesday at a listing for Dora Franczak in Oak Lawn told the AP she declined to comment about the reopening of the investigation, saying, "I don't have any remarks about that." In June, she spoke briefly to the Sun-Times, telling the paper, "We went through this once, and we certainly don't want to go through this again."

Paul Fronczak told KLAS-TV in Las Vegas this year that he is still trying to learn his true identity.

"I don't know how old I am, or who I am, or what nationality, all those things you just take for granted," Fronczak said.

The Associated Press contributed to this report.

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