PHILADELPHIA (AP) — The body of a 19th-century serial killer is being exhumed in suburban Philadelphia at the request of his great-grandchildren, who hope identifying his remains will quell centuries-old rumors that he conned his way out of his execution and escaped from prison.

A Delaware County judge gave the go-ahead to the exhumation of the remains of Dr. H. H. Holmes in a court order dated March 9.

Holmes killed dozens of people at his hotel of horrors during the 1893 Chicago World’s Fair. It featured gas chambers and an industrial oven in the basement.

But it was the murder of his business partner that led to his conviction and hanging in Philadelphia in 1896.

Holmes was the subject of the 2003 best-selling book, “The Devil in the White City,” by Erik Larson.