An Italian museum crammed full of skulls, brains and skeletons of 19th century criminals is facing calls from their descendants to return the body parts.

Stuffed with its gruesome exhibits, the Museum of Criminal Anthropology in Turin represents the life's work of Cesare Lombroso, an Italian physician and psychiatrist who began his collection in 1878.

Hundreds of wax-covered heads line the shelves, some with the words "Thief" or "Murderer" written underneath, all form part of Lombroso's research into the nature of criminal behaviour.

Many of the body parts on display in the museum were taken from prisons without any permission from family members, and now, hundreds of years later, some distant relatives and local communities are saying it is time to get the remains returned.

However, the museum's director is convinced that the collection should remain intact, as Lombroso intended.

"Yes, they are human remains, but also they are an historic document because Lambroso left an inscription on this skull. So it has a double meaning. It's not just a human skull, it's also a document - an important testimony to historic scientific methods from the 1800s," he explained.