To "inter" a body is to bury it or place it in a mausoleum, so to disinter someone is to take the body out again — usually to find out how they died, to make sure it's really who we think it is, or to move the body to a new burial site.
You might think you got away with murder, but once they disinter the body, the medical examiners will find out that the guy was a victim of your evil plot. A vampire sleeps all day in his own coffin and then disinters himself at night to go in search of blood. One way to remember the meaning of disinter is to think of "dis-entering" a body. When someone dies, their body is "entered" into the grave. If the body is removed, it's being "dis-entered," in a sense. But disinter is spelled — and pronounced — differently (diss-in-TUR), of course.