When a girl playing treasure hunt reached underneath a floorboard of her family's historic Michigan home last January, she had no idea of the mystery she was about to unearth -- four partial sets of human remains dating back more than 100 years that authorities say could be connected to the Underground Railroad.
Months after their discovery, the still-unidentified remains will be laid to rest Saturday in a 19th century-style ceremony in Union City, about 65 miles southeast of Grand Rapids. A horse-drawn hearse will carry the bones of two males and two females from the First Congregational Church to their final resting place -- a donated cemetery plot at Riverside Cemetery -- while townspeople dressed in period clothing look on.
But for the residents of Union City, the story behind the bones is far from being laid to rest.
"It's a real mystery," said town historian Martin Chard. "It’s odd that somebody would keep different bones like that from different people. There's not a full body there at all -- there's no head, no feet, no hands."
Bryant and Teasha McIntosh recently purchased the three-story home, which was built in 1839 and which once served as a hideout for slaves escaping by way of the Underground Railroad.
The home -- the second oldest in Union City -- was originally owned by the family of John D. Zimmerman, a local blacksmith and stationmaster for the Underground Railroad, who concealed slaves inside his home and helped them flee to Canada. At the time, Union City was designated "Station No. 2" of the secret network that assisted slaves in their quest for freedom.
The mystery of the bones unfolded last winter when the McIntosh family began to restore the home that was in desperate need of repair.
Bryan McIntosh said he was drilling a hole in the ceiling of his daughter's bedroom one day when an old book fell from behind the wall. The discovery of the book prompted McIntosh's two teenage daughters, 13 and 16, to scour the home for other artifacts -- including a search of the attic.
On Jan. 12, one of the girls reached with her hand beneath one of the attic floorboards and felt an object.
"She thought it was a doorknob," Lt. Chris Mathis of the Union City Police Department told FoxNews.com. "When she pulled it out, she saw it was a bone."
The startling discovery prompted the family to tear up all the floorboards in the attic. Four partial sets of human remains and an 18th-century corset were found hidden beneath, Mathis said.
Were the four individuals victims of a crime, or were their partial remains placed there after their deaths?
"That's the million-dollar question," Mathis said. "Just the fact that they're underneath the floorboards is strange."
"It's hard to think of a reason that isn't a nefarious one," he said. "But there's nothing that suggests a crime, either."
The bones -- which included a lower jaw with teeth, vertebrae and ribs -- were sent to Michigan State University's forensics lab where it was determined they dated back more than 100 years and "were a collection of anatomical specimens from different individuals."
Once forensic anthropologists determined that no current crime had been committed, they abandoned efforts to uncover the age and race of the individuals.
"That's where the investigation stopped," said Chard, whose wife, Emily, coincidentally lived in the home as a young girl in the 1960s. "The expense of trying to figure out anything else outweighed any advantage."
"It definitely would have been interesting to know the race of them," he said. "Then you could surmise whether there was any connection to the Underground Railroad."
Zimmerman, originally from Fairfield, Conn., moved with his family to Union City in the spring of 1838. His home soon served as a hiding place for slaves seeking refuge.
Mathis said hundreds of thousands of slaves went through the Zimmerman home on their way to Canada.
"They were, of course, all undocumented," he said. "And we don't know how many."
Mathis also said the corset found with the bones was "not typical garb for a slave to have," though noted that it could have been a "hand-me-down" given to a slave along the way.
Chard said one theory being considered is that the remains were placed there because the town cemetery may not have been completed.
"People would bury someone in the backyard of their home," Chard said. "I don’t know if someone got dug up partially, possibly by an animal ... Maybe they [the homeowner] decided to keep a bone of each person."
A second theory suggests the remains belong to slaves who could not be buried next to white people.
SEND TIPS TO NEWSMANAGER@FOXNEWS.COM
Cristina Corbin is a Fox News reporter based in New York. Follow her on Twitter @CristinaCorbin.