Thomas Kneir, FBI special agent in charge, said the DNA tests were conclusive that the boy is not Tristen "Buddy" Myers. Authorities said the boy's DNA had been compared with Buddy's mother, Raven Myers.
"I wish I were here to give you and more importantly, the family of Tristen ... Myers some good news. Unfortunately, that is not the case," Kneir said.
"The two children are not identical," he said.
Buddy hasn't been seen since he and his great aunt, Donna Myers, nodded off while watching a videotape on Oct. 5, 2000, at the rural home they shared in Roseboro, about 60 miles south of Raleigh.
When she awoke, Donna Myers discovered Buddy and two of the family dogs were gone. The dogs returned home day later, but Buddy, then 4, was never found.
The investigation into the Illinois boy's identity — and possible connections to Buddy — began after Ricky Quick took a boy he said was his son Eli to a hospital in Evanston in February to be evaluated for aggressive behavior.
Officials said Eli hadn't bathed or changed clothes in days, so juvenile officials were called and the child was placed in foster care.
The Illinois Department of Children and Family Services also circulated the youngster's picture to the National Center for Missing and Exploited Children and found the reports of Buddy's disappearance.
Eli's face, lisp and scars strongly resembled a description and photo of Buddy. Investigators retrieved DNA samples from the child and from Raven Myers, who gave birth to Buddy when she was 15 years old.
Quick has repeatedly said he fathered the child with a prostitute named Laura who gave him the infant and asked him to raise the boy.
On Thursday, a woman who lives in southern Illinois came forward saying the boy was born to her sister, Laura. Cheri Trandel said her sister had handed the baby over to Ricky Quick years ago.
Cook County records also show that a woman named Laura Trandel gave birth to Timothy Robert Trandel at a Chicago hospital in 1996. Criminal records also show Laura Trandel was arrested for prostitution at least a dozen times.
"My sister had a little boy. That's him," Cheri Trandel told the Chicago Sun-Times for Friday editions.
Cheri Trandel said she is raising three of her sister's children and has contacted the state about the boy. "If I could step in, I would want him," she said.
Eli remained in foster care Friday, authorities said.