MELVILLE, N.Y. - DNA tests have determined that the assertions of a Michigan man who believed he may have been abducted as a toddler on Long Island 54 years ago were unfounded, the FBI said yesterday.

The FBI said DNA tests conducted on John Robert Barnes, of Kalkaska, Mich., found he could not be Steven Craig Damman, who disappeared on Oct. 31, 1955, after his mother left him in front of a store in East Meadow, N.Y., while she shopped.

In addition, a birth certificate obtained by Newsday yesterday shows that Barnes was born on Aug. 18, 1955, in Pensacola, Fla., making him less than 3 months old at the time of the disappearance. Damman was nearly 3 years old when he vanished.

Barnes' father, Richard Barnes, this week called his son's story "bull" and said he had been his father his entire life. He said his son was born at a Navy hospital in Penascola, Fla., on Aug. 18, 1955. "We brought him home two days later," the elder Barnes said. "And he's never been out of our sight."

He said he and his son were estranged and had not spoken for several years even though they live about eight miles apart in Michigan.

The case had raised the hopes of the toddler's father, Jerry Damman, who runs a 440-acre farm in Iowa. Damman, 78, had said he hoped for a resolution after five decades.

"It's too bad we had to go through all of this for actually nothing in the end," he told the Associated Press.

Appearing on NBC's Today show yesterday morning, John Barnes said he always had had a nagging feeling he wasn't who his parents said he was.

"As I got older," he said, "I realized how different I was from my mother and father and that something wasn't right. . . . I wasn't sure if I was kidnapped or switched at birth or adopted. I just knew I didn't come from these people." Barnes has been at the center of an FBI probe trying to determine if he is Steven Craig Damman.

The disappeared child's mother, Marilyn Damman, told Nassau County police that she had gone to the supermarket for a loaf of bread, leaving 2-year, 10-month-old Steven outside with his 7-month-old sister, Pamela, who was in a stroller. When the young mother came back outside, she said, her two children were gone.

Pamela Damman was found in the stroller around the corner from the store.

Steven Damman has not been seen since.

Barnes said he began searching his past after the death about 10 years ago of the woman who raised him. It has been reported that Barnes claimed the woman, on her deathbed, had told him he was not her son. On the Today show, Barnes said that was not true.

Also appearing on Today was Pamela Sue Horne, Steven Damman's younger sister, who said, before the DNA tests were revealed, that she believed there was a good chance John Barnes was her long-missing brother.

The mother divorced Jerry Damman within a year or so after their son vanished. Now known as Marilyn Kimberlin, she is confined to a nursing home in Grain Valley, Mo., and is said to be unaware of the new developments.

This article contains information from the Associated Press.