An 1853 newspaper ad placed in Jornal do Commercio by Brazilian entrepreneur Damaso Antonio de Moura was the final piece to a puzzle that had perplexed Maryland history professor Daryle Williams for months.

The ad in the Brazilian publication sought help in tracking down a runaway slave named José Congo, who had a wooden leg. Using the biographical information in the ad, Mr. Williams identified him as a man who was enslaved in west Africa in 1833. The man was illegally trafficked to Brazil, where he eventually had his leg amputated and replaced with a wooden peg leg before escaping.

“You can see the excitement in Daryle. It’s like detective work,” says Dean Rehberger, the director of Matrix: The Center for Digital Humanities and Social Sciences at Michigan State University.

Mr. Williams excitedly recounted his research findings while videoconferencing recently with Mr. Rehberger and Walter Hawthorne, chairman of the Michigan State’s department of history.

José’s story is the latest research to be added to “Enslaved: The People of the Historic Slave Trade,” an online hub of worldwide slave trade data being developed at Michigan State by Mr. Rehberger and Mr. Hawthorne with the help of a $1.5 million grant from the Andrew W. Mellon Foundation. More information can be found at enslaved.org.