PHOTO: Fort Bend Independent School District
Now playing
00:49
See the burial site of nearly a hundred slaves
Now playing
00:50
This massive cave was discovered in China
An expert works to uncover one of the 20 wooden sculptures which were recently discovered at the ancient archaeological site of Chan Chan, in the outskirts of the northern city of Trujillo, in Peru, on October 22, 2018, - The unique sculptures found in niches are fixed to the ground measuring an average of 70 centimeters and representing different characters. (Photo by CRIS BOURONCLE / AFP) / The erroneous mention[s] appearing in the metadata of this photo by CRIS BOURONCLE has been modified in AFP systems in the following manner: [20] instead of [19]. Please immediately remove the erroneous mention[s] from all your online services and delete it (them) from your servers. If you have been authorized by AFP to distribute it (them) to third parties, please ensure that the same actions are carried out by them. Failure to promptly comply with these instructions will entail liability on your part for any continued or post notification usage. Therefore we thank you very much for all your attention and prompt action. We are sorry for the inconvenience this notification may cause and remain at your disposal for any further information you may require.        (Photo credit should read CRIS BOURONCLE/AFP/Getty Images)
PHOTO: CRIS BOURONCLE/AFP/AFP/Getty Images
An expert works to uncover one of the 20 wooden sculptures which were recently discovered at the ancient archaeological site of Chan Chan, in the outskirts of the northern city of Trujillo, in Peru, on October 22, 2018, - The unique sculptures found in niches are fixed to the ground measuring an average of 70 centimeters and representing different characters. (Photo by CRIS BOURONCLE / AFP) / The erroneous mention[s] appearing in the metadata of this photo by CRIS BOURONCLE has been modified in AFP systems in the following manner: [20] instead of [19]. Please immediately remove the erroneous mention[s] from all your online services and delete it (them) from your servers. If you have been authorized by AFP to distribute it (them) to third parties, please ensure that the same actions are carried out by them. Failure to promptly comply with these instructions will entail liability on your part for any continued or post notification usage. Therefore we thank you very much for all your attention and prompt action. We are sorry for the inconvenience this notification may cause and remain at your disposal for any further information you may require. (Photo credit should read CRIS BOURONCLE/AFP/Getty Images)
Now playing
01:00
Centuries-old sculptures discovered in Peru
PHOTO: Courtesy Rick Aster
Now playing
01:15
Eerie hum discovered in Antarctica
Alvin collects a sample of Lophelia pertusa from an extensive mound of both dead and live coral.
PHOTO: Woods Hole Oceanographic Institute
Alvin collects a sample of Lophelia pertusa from an extensive mound of both dead and live coral.
Now playing
01:00
Deep-sea coral reef discovered off US coast
Organic matter found Mars orig dlewis vstop_00000000.jpg
PHOTO: NASA
Organic matter found Mars orig dlewis vstop_00000000.jpg
Now playing
00:56
Organic matter found on Mars
The USS Juneau In New York Harbor, 11 February 1942.
PHOTO: Courtesy the U.S. National Archives.
The USS Juneau In New York Harbor, 11 February 1942.
Now playing
00:58
Wreck of sunken US WWII warship discovered
PHOTO: Hakai Institute
Now playing
01:07
14,000-year-old ice age village discovered
PHOTO: Getty Images
Now playing
00:56
Study suggests water in moon's interior
CAIRO, EGYPT - OCTOBER 21: Camels and horses stand tied to a fence below the Great Pyramid of Giza on October 21, 2013 in Cairo, Egypt. The Pyramids of Giza, one of the seven wonders of the ancient world and built around 2600 B.C., are one of Egypt
PHOTO: Ed Giles/Getty Images
CAIRO, EGYPT - OCTOBER 21: Camels and horses stand tied to a fence below the Great Pyramid of Giza on October 21, 2013 in Cairo, Egypt. The Pyramids of Giza, one of the seven wonders of the ancient world and built around 2600 B.C., are one of Egypt's major tourist drawcards. After a summer of violence, tourist numbers across Egypt are at their lowest levels since a 2010 peak in tourism in the country. While Egypt's tourism sector took a dive following the popular uprising that overthrew President Hosni Mubarak in early 2011, occupancy rates of hotels in the capital Cairo and across Egypt have been reported as dramatically down since the Egyptian military's overthrow of President Morsi in July. In 2010, tourism represented 13% of Egypt's economy and employed one in seven of the country's workers. (Photo by Ed Giles/Getty Images).
Now playing
01:01
Mysterious void discovered in Great Pyramid
PHOTO: The Leakey Foundation
Now playing
01:08
What a 13-million-year-old ape skull reveals
PHOTO: Courtesy Jean-Jacques Hublin/MPI-EVA, Leipzig
Now playing
00:54
Earliest known Homo sapiens fossils discovered
A scientist at the Max Planck Institute for the Science of Human History looks at a jaw bone. Bone, soft tissue and teeth were all studied as part of the research,
PHOTO: courtesy Max Planck Institute for the Science of Human History
A scientist at the Max Planck Institute for the Science of Human History looks at a jaw bone. Bone, soft tissue and teeth were all studied as part of the research,
Now playing
00:50
DNA discovery reveals genetic history
PHOTO: Nature Communications
Now playing
01:05
Scientists create artificial womb
vikings site space satellite north america orig jnd vstop_00003920.jpg
PHOTO: NOVA
vikings site space satellite north america orig jnd vstop_00003920.jpg
Now playing
01:05
Potential Vikings site found in North America
coral fossil university of iowa pkg _00000426.jpg
PHOTO: KGAN
coral fossil university of iowa pkg _00000426.jpg
Now playing
01:14
Construction crew uncovers 385-million-year-old fossils
(CNN) —  

Months after a Texas school district broke ground on a new technical center, archaeologists there made a surprising discovery: the long-buried remains of 95 people.

The first remains were discovered in February in Sugar Land, a suburb southwest of Houston. And now officials have learned who these people probably were – freed black people forced to work in convict labor camps.

For over a century, these graves were underground and untouched. But the finding that they likely held the remains of slaves, which researchers announced Monday, highlights an era that’s largely forgotten in history – a time when slavery was illegal, but many blacks were essentially still enslaved.

The Sugar Land property is owned by the Fort Bend Independent School District, which is building its new technical school on the land.

“It’s a remarkable opportunity for our community and our school district to learn much more about the history of our local region,” Superintendent Charles Dupre said in a statement.

The site’s archaeological project manager agrees.

“It’s a rare opportunity,” Reign Clark of Goshawk Environmental Consulting told CNN. “We’ll be telling the story of what it was like to live here, work here, and, in some cases, die here.”

How they were found

It started with a hunch.

Reginald Moore took an interest in historical cemeteries after working as a Texas state prison guard in the 1980s. He no longer works at the prison, but he’s still a community activist.

One of his main focuses: getting people to recognize the abuses of the Sugar Land convict-leasing system, in which prison inmates were forced into labor.

“I felt like I had the duty to be an advocate for them and to speak from the grave for these people,” Moore told CNN.

Researchers
PHOTO: Fort Bend Independent School District
Researchers' drawings of the remains. The slaves were overworked and malnourished.

Moore is the caretaker of another cemetery in Fort Bend County: the Imperial Farm Cemetery, which is nestled behind a shopping center off the highway. Near the cemetery is the home of the school district’s new James Reese Career and Technical Center.

So when construction on the Sugar Land school’s center started last fall, Moore told officials that other cemeteries might be nearby.

“He has documented and provided a lot of information about the history of that cemetery. He has a lot of ideas where the burials could’ve been,” said Chris Florance of the Texas Historical Commission, which has played an advisory role in the project.

What they found

The bodies were each buried in individual wooden caskets. Of those analyzed so far, all but one are men. Researchers say they could have been as young as 14 and as old as 70.

They were probably buried between 1878 and 1910, Clark said.

Despite the passage of time, researchers can tell that the workers were malnourished or sick and faced huge physical stress when they were alive.

Clark said there’s lots of evidence that they were doing very heavy labor that, for some, began at a young age.

“We can tell from the state of the bone and muscle attachment features that these were heavily built individuals. Some bones were misshapen by the sheer musculature and labor,” Clark told CNN.

It’s no surprise in Texas

Moore wasn’t the only one who wasn’t shocked at the discovery. Florance said his commission took a role in the project knowing a find like this could happen.

“It’s not uncommon in Texas,” he told CNN.

What was shocking, though, was how hard the graves were to find. The commission had done assessments before construction began, Florance said, but the land was so altered over the years that it was hard to know anything would be there.

“One of the biggest problems with old cemeteries is that the markers might have gone away. There’s no surface evidence,” he said.

The are 177 cemeteries in Fort Bend County, but there could be as many as 50,000 cemeteries across the state. Only 1,706 have a historic Texas cemetery designation.

The ‘Hellhole on the Brazos’

President Lincoln’s 1863 Emancipation Proclamation said all slaves who lived in states that had seceded from the US were free. The 13th Amendment, ratified in 1865, formally abolished slavery in all of the US.

That doesn’t mean forced labor didn’t continue.

After the Civil War ended in 1865 and slaves were outlawed, the Texas economy dropped into a deep depression. Businesses needed a new form of cheap labor. So they resorted to prisons.

The convict-leasing system was essentially slavery all over again. Prisoners were taken from state prisons and leased to private businesspeople who worked the laborers as hard as they could for the cheapest price. And the less food, water and shelter these workers got, the less they cost.

“One 14-year-old was 6 feet tall,” Clark told CNN. “This population was hand-selected.”

Sugar Land’s economy had thrived on sugar cane plantations, which largely relied on slave labor. So two Confederate veterans, Edward Cunningham and Littleberry Ellis, signed a contract with the state in 1878 to lease the state’s prison population.

Conditions were so bad that the city got itself a nickname: “Hellhole on the Brazos.”

“It had the worst reputation of all the prison farms in Texas,” sociologist Richard Vogel told CNN affiliate KTRK.

What happens next

Digging up and analyzing all 95 graves takes serious time – likely more than nine months’ worth of work.

Each unburial takes up to two days, plus up to eight hours of cleaning and up to 15 hours for analysis, the school district said. So far, they’ve dug up 50 graves and analyzed more than 22, Clark said.

Once they’re dug up, a team of forensic archaeologists will look for more information on the corpses, such as their medical conditions and how they died. After that, the school district will work with the state’s historical commission to figure out where to rebury them.

Moore wants to get a memorial for the group as a form of restitution.

“I’m speaking for those who didn’t have a voice, then and now,” he told CNN. “I felt like I was called to set them free.”

Correction: A previous version of this story incorrectly stated the Emancipation Proclamation freed all slaves. The proclamation said all slaves held in states that had seceded from the United States were free. The story also corrects the date of the Emancipation Proclamation.