TRENTON -- The N.J. State Police is awaiting DNA test results on a possible match for Melissa Diane McGuinn, who disappeared from Trenton in 1988 when she was 7 months old, authorities said today.

Three previous DNA tests on women who believed they could be a match for the missing girl have been returned negative. A social media campaign to "Find Baby Melissa" and recent news stories renewed interest in the decades old case.

At least one of the four women who have been tested asked police to be included, Trooper Jeff Flynn said.

"There are a lot of people out there who don't know where they came from," Flynn said. "Maybe they were adopted under strange circumstances. This is part of our driving force to get this (story) out nationally to find someone who maybe doesn't know where they came from. And if they fit the age and the background, we can test it.''

The ability to test DNA for possible identification is a recent development, said State Police Detective Paul Sciortino, one of the lead investigators on the case.

State Police took over the investigation from the Trenton Police in 2008, Sciortino said. That's when investigators discovered that hospitals in the state were required to keep blood samples from every newborn baby on file for 23 years, Sciortino said.

The time was just about to expire on Melissa's sample, Sciortino said.

Since then, a woman from the Netherlands, one in Iowa and a third from California have had their DNA tested. All have been ruled, out, Sciortino said.

The woman currently being tested was recommended to police by her half-brother. She lives in Texas, Sciortino said. It is the only lead in the case, he said.

The results of the latest DNA test are not expected until September or October, Sciortino said.

The Times of Trenton detailed in March the first visit by Melissa's mother, Rebecca House, to the scene of the disappearance since 1988. House stood beside her former Trenton home and expressed hope that someday, her daughter would be found.

House has never given up hope that her only daughter is still alive, despite the strange circumstance under which she disappeared.

House’s roommate had taken the baby outside the Lamberton Street home they shared on the morning of March 6, 1988, and came back without the child just minutes later.

At first, the roommate, Wanda Faye Reed, had said a man knocked her down and took Melissa. Then she said she gave the baby to a man in a car. Finally, she claimed she threw the infant into the icy Delaware River a short distance away.

Reed suffered from a mental disability, and her versions of what happened have always been in doubt. Despite intense searches on land and water in 1988, no trace of Melissa has ever been found.

When House visited the residence where Melissa disappeared with The Times of Trenton earlier this year, she wore on her right wrist a charm bracelet, pink and silver, with a mother’s inscription on it.

“That represents Melissa,” House said, flipping the bracelet so the dangling heart on the piece of jewelry rests on her wrist. “She’s my only daughter.”

Keith Brown may be reached at kbrown@njtimes.com. Follow him on Twitter @KBrownTrenton. Find The Times of Trenton on Facebook.