The New York City medical examiner's office is digging up dozens of unidentified bodies buried in the city's potter's field as part of a new push to help solve missing-persons cases that have languished for years.

In recent months, 54 bodies have been exhumed from Hart Island, in the Long Island Sound near City Island, where more than 800,000 people are buried.

Most of them are poor citizens whose identities were known and who needed a city burial, officials say. But the unidentified include runaways, the homeless or regular civilians whose families lost track of them. And now dozens of positive identifications are being made, thanks to improved DNA technology that can tell, among other things, whether the body was male or female, and roughly how old he or she was.

Many of the advances in technology were lessons learned from identifying human remains recovered at the World Trade Center site, officials say. 

Encouraged by the success, the medical examiner's office applied for and received a grant from the National Institute of Justice to continue its work. Investigators are now poring over decades of records.

"We have about 1,200 cases that we are working on that go to the late 1980s," said Dr. Benjamin Figueroa, who's helping to supervise the search effort. 

"We can go back now and say, for example, it's actually a black female age 17 to 25," said Dr. Bradley Adams. "There's work we can do now with forensic anthropology which couldn't be done back in the time."

Scientists at the city's new forensic lab are now busy entering DNA samples from the exhumed bodies into local and national databases. But that's only the start of the process in solving missing person cases, assistant lab director Mark Desire says.

"Equally challenging is to get a DNA profile to compare it to a family," said Desire. "Part of the big push is to make sure reference families' samples get in the system."

Without a DNA sample from relatives, cases often cannot be solved. If those buried are from out of state or overseas, it's especially difficult to make the match.

That appears to be the case with "Baby Hope," the 6-year-old girl whose starved body was found stuffed in a cooler in the woods off the Henry Hudson Parkway in 1991.

"You have information that can make a very straightforward identification, but nobody is looking for that child," said Adams. "Otherwise, there would be a DNA hit. It's hard to believe you'd have a child... that's still unidentified."

In cases where a DNA match fails, scientists may turn to a national website called NAMUS, which lists missing-person cases, along with bodies of the unidentified and photos of clothing found on the bodies. The public and the families of missing persons can log on and try to solve the mysteries.

"The great thing about NAMUS is there is a whole community of volunteers and cybersleuths... who will analyze what we put on the website," said  Figueroa. “There have been a number of times where somebody from the general public has pointed us to a missing person in connection with one of our unidentified."

"We don't pass judgment on who that person was," said  Figueroa. "If there is something that can be done, we're going to do it. It's our job to identify that person. Doesn't matter if that case came in today or 20 years ago."

Families can move forward, both legally and financially, once they have a death certificate in their hands, officials said. But more importantly, they can provide emotional closure. Families can finally have answers and try to bring their loved one back home so relatives can have one last goodbye.

In Queens, Gloria Chait, 83, has held on to her son Steven's belongings and has renderings of what her son might look like now, decades after he disappeared from his dorm room at Columbia University in 1972.

"I love this kid," said Gloria Chait, who still keeps Steven's belongings in his room in their Fresh Meadows home. "No one wants to go 40 years not knowing where your child is."

But she also has a grim hope that the city's new push to identify the "lost souls" of Hart Island may finally give her answers as to what happened to Steven.

"You can't be cynical about this. You have to be realistic and a bit optimistic," said Chait. "You have to understand what kind of suffering goes with a person that disappears. It is immeasurable."

Get the latest from NBC 4 New York anytime, anywhere. Follow us on Twitter, Facebook and Google+. Get our apps here and sign up for email newsletters here. Get breaking news delivered right to your phone -- just text NYBREAKING to 639710. For more info, text HELP. To end, text STOP. Message and data rates may apply.