The woodsy site where the bones were found is known as Duffy's Cut. It is named after Philip Duffy, who hired the immigrants from Donegal, Tyrone and Derry to help build the Philadelphia and Columbia Railroad.

Years of combing the several acres of rough terrain in Duffy's Cut had so far yielded about 2,000 artifacts, including pipes, buttons and forks. Then on Friday, researchers using ground-penetrating radar unearthed pieces of two skulls along with dozens of other bone fragments and teeth. The findings were announced Tuesday.

Research led Watson to conclude many of the Irish workers died of cholera, an acute intestinal infection caused by contaminated food or water that typically had a mortality rate of 40 percent to 60 percent.

Watson believes some of the workers may have been murdered because of their illness or ethnicity. There was general prejudice against Irish Catholics, tension between residents and the transient workers, and a great fear of cholera — especially among the affluent classes, Watson said.

Anyone with cholera "was deemed to be almost subhuman," Watson said. "God forbid it would spread to the respectable segments of society."

Researchers including University of Pennsylvania geosciences professor Tim Bechtel expect to find bullets buried with the bones.

"Every shovelful of dirt that comes out of there ought to be sifted," Bechtel said.

The immigrants were buried anonymously in a ditch outside what is now Malvern, about 30 miles west of Philadelphia. All day long trains travel past the site, which backs up to a manicured subdivision in East Whiteland Township.

Watson and his twin brother, Frank, also a historian, started the Duffy's Cut Project in 2003, a year after learning of the workers and their demise from the personal papers of their late grandfather, who had worked for the railroad much later on.

Watson said they have discovered the names of 15 of the 57 immigrants with help from a ship's passenger list, and even have tentatively identified one set of remains as that of John Ruddy, a teenager.

Researchers plan to extract DNA from the bones and find living descendants of the men in Ireland. The goal is to identify them all and either repatriate their remains or give them proper burials, Watson said.

The railroad never informed the men's families of their deaths and instead allowed the bodies to be "thrown into a ditch and treated like garbage," Watson said.

"This was someone's son or brother or husband," he said. "Something has to be done."

Breandan O'Caollai, deputy consul general of Ireland in New York, praised the Watson brothers for their commitment to the project.

"This is a very important discovery that will help bring some closure to a very sad chapter in Irish-American history," O'Caollai said.

http://news.yahoo.com/s/ap/20090325/ap_on_re_us/irish_immigrants_grave/print