Human Bodies on Display: Where Do They Come From?

A Brian Ross undercover investigation into exhibits that millions pay to see.

Feb. 13, 2008— -- Click here to read an update on this story.

Plasticized bodies — every vein, muscle, organ and bone of what was once a real person, carefully preserved in ways that were not possible before — have become blockbuster attractions across the country. Millions of people have paid to see the bodies that are put on display in a full range of poses, such as running with a football or dancing.

But with the growing popularity have come troubling questions about the bodies. Whose bodies are they? Where do they come from? And is it educational and scientific, as some people say, or are these cadavers just being used for entertainment?

A three-month "20/20" investigation into the business of bodies tracked the ghoulish process to its origins — from a body processing factory on the German-Polish border, to Internet sites that offer the plasticized bodies for sale, to a rundown warehouse in northern China where "20/20's" undercover cameras saw what has, until now, been kept well hidden.

Watch ABC News Chief Investigative Correspondent Brian Ross' exclusive investigation Friday on "20/20" at 10 p.m. ET.