Tests show that the remains in a suburban Philadelphia grave are indeed those of a 19th century serial killer, quelling rumors that he had conned his way out of execution and escaped from prison.
A judge approved the exhumation of Dr. H. H. Holmes' grave earlier this year.
Descendants requested it for a series called "American Ripper" on the History Channel. Part of the show looked at whether Holmes escaped, and scientists' findings were revealed in this week's final episode.
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.