Recently I have come across an article about body snatching in London and an History Detectives episode that examined a cemetery alarm from the 1800s meant to prevent body snatching. Body snatching is the obtainment of human cadavers (stolen from the grave) to sell to medical schools to dissect. It has been around since the 14th century and was particularly problematic in England during the 1700s and 1800s. It was also a problem in the US. The NIH has put together an informative article on the history of body snatching for those who would like more information.
The History Detectives episode hit a little closer to home, examining an artifact that ended up being connected to grave robbery in the 1800s in Ohio. During the mid to late 1800s, medical schools would buy or steal cadavers to educate their students in gross anatomy.
In 1878, a newspaper article describes how the body of John Scott Harrison, father of future president Benjamin Harrison, was found in a medical school by his own son, who was searching for the body of a friend whose grave had been robbed. You can imagine how his son must have felt. This theft occurred despite precautions the family had taken, including hiring watchmen a d placing weights that would require many men to lift them.
As a result of this and other body snatching, people turned to explosive devices, including the one that is featured in the History Detectives episode.
How did your ancestors protect their dead during this time? Were they affected by body snatching?
bridgingthepast.com 
I had a terrible case of body snatching in my family history. It was 1819 in Chebacco Parish of Ipswich, Massachusetts (now the town of Essex). I blogged about it at this link http://nutfieldgenealogy.blogspot.com/2010/04/body-snatchers-1819.html The culprit was a local doctor.