The find, called the Duffy's Cut Project, started out as an investigation into local folklore and ghost stories. It has since transformed not only into a significant historical find but also, perhaps, one of the oldest murder mysteries in the Keystone State.
"All the remains found so far indicate [the men] were brutally murdered," William Watson, head of the history department at Immaculata University in Immaculata, Pa., told AOL News. "Some of them were just bludgeoned [to death]. It's unbelievable."
"Duffy's Cut," as it's known, is a stretch of rail line in Malvern, 30 miles west of Philadelphia. It was constructed for the Philadelphia and Columbia Railroad in 1832. Much of the construction was completed by a group of 57 Irish immigrants from Donegal, Tyrone and Derry, Ireland, who arrived in Philadelphia in June 1832 aboard the ship John Stamp.
"They came here to partake of the American dream," Watson said. "No doubt, they thought they were going to get some good work, and they were hired right off the docks by a fellow Irishman named Philip Duffy, who came in around the War of 1812. He basically brought them out here to complete the most expensive and difficult mile in the entire Philadelphia and Columbia system."
Within eight weeks of their arrival, all 57 reportedly died during a cholera pandemic. The dead were buried together in a mass grave along Duffy's Cut.
The fate of the men who lost their lives was all but forgotten by the time Watson and his twin brother, the Rev. Frank Watson, were born. By then, the story of the men's deaths had transformed into more of a local legend.
"It was the kind of story that was dimly remembered, very incorrectly, in local folklore," William Watson said. "Our grandfather enjoyed talking about the ghost story aspect of it."
The Watsons' grandfather had worked for the Pennsylvania Railroad and was knowledgeable of the tales. His ghost stories included an account of a man who, in the years following the incident, claimed he was walking along the tracks when he saw ghosts dancing on top of the Irish workers' graves.
Following the death of their grandfather, the brothers inherited a box of old railroad files. When they were going through them together in 2002, they found documents from 1909 that contained contextual evidence of the deaths and the approximate location of the mass grave.
"It was one of those things that had to be investigated," Watson said. "We started looking to see if there was any reality behind the dimly remembered stuff, so we began looking into Pennsylvania archives and flushed it out even further."
By 2004, the Watson twins had assembled enough documented evidence of the deaths to have a historical marker placed on the site.
"Nearby is the mass grave of fifty-seven Irish immigrant workers who died in August, 1832, of cholera," the marker reads. "They had recently arrived in the United States and were employed by a construction contractor named Duffy ... Prejudice against Irish Catholics contributed to the denial of care to the workers. Their illness and death typified the hazards faced by many 19th-century immigrant industrial workers."
Once the marker was in place, the Watsons began an archaeological dig at the site of the Irish workers' camp. Before long, they managed to unearth over 1,000 artifacts, including an old clay pipe with an Irish logo and a bowl inscribed with the words "Flag of Ireland."
The dig went on for three years, but the remains of the men continued to elude the Watsons and their team of volunteers. Then, in 2007, geophysicist Timothy Bechtel agreed to help. He brought with him a sophisticated ground-penetrating radar system, which literally allowed the team to X-ray the soil in the surrounding area.
"[Bechtel] found something in 2008," Watson said. "He said, 'You guys should dig here.' We processed the data and, in March 2009, we were able to find the first set of [human] remains very precisely, [thanks to] his science."
Since the first discovery was made, Janet Monge, an anthropologist from the University of Pennsylvania, has identified four human skulls and bones from seven skeletons. Those skeletons, however, suggest something other than a cholera pandemic may have claimed the men's lives.
"Skeleton number six looks like it has a bullet hole in it, and we have very good indications of blunt-force trauma to the others," Monge told AOL News. "Last year, when we only had two skulls to examine, I was a bit hesitant in claiming that we were looking at traumatic death, but this year, in every specimen that we examine, it really seems to indicate that they were victims of blunt-force trauma around the time of death."
Monge says the conditions of the remains make it impossible to determine whether the men had suffered from cholera, but she said she might be able to determine whether the hole in skull No. 6 was caused by a bullet hole.
"We want to conduct a lead test in the area around the hole itself, because lead bullets often times shed a bit of their lead as they enter into the bone," Monge said. "Then we have to research the kind of bullet and compare it to other specimens; for example, [the remains of] soldiers at Little Big Horn that had similar kinds of wounds and damage."
If the men were murdered, as Monge and the other team members suspect, what would be the motive? Watson says he and his brother already have a theory.
"There is a newspaper account from October 3, 1832, about cholera striking the camp," Watson said. "Some of the men panicked and tried to get out and were forced back in. Another article, from November 1832, says the earlier story was not accurate and that there were only eight or nine men [who] died."
As a result of the brothers' research and the evidence found upon the skeletal remains, the Watsons suspect local vigilantes killed most of the workers.
"The fact is, they were murdered," Watson said. "In the first layer of burials, we suspect most of the men are going to be victims of cholera, which leaves no physical traces. But, we believe the others were killed to make sure there would be no cholera getting out of that valley."
According to Watson, it could take several more years of digging to fully excavate the area and uncover the rest of the men's remains. Once that work is completed, he says, they will not be displayed in a museum and will instead be given proper burials.
"We have a cemetery to take them to, which is really perfect because where they are now is essentially a dumping ground," Watson said. "It is West Laurel Hill Cemetery in Bala Cynwyd, just outside of Philadelphia. It is where a lot of the Victorian elite of Philadelphia are buried."
In the meantime, Watson and his group will continue to hunt for clues to determine whether the men of "Duffy's Cut" were the unfortunate victims of an acute illness or whether something far more sinister claimed their lives.
"We have to dig them up," Watson said. "It is very hard work -- we are kind of doing the same kind of work the men themselves did in 1832 -- but they deserve to have their story told."