Once an area of interest has been identified through proper search techniques and often with help of police informants, any artefacts or remains should be excavated in a way that maximises the recovery of such evidence while minimising intrusion. By nature excavatation is a destructive and unrepeatable event and while there are a number of methods that have been used historically (pedestalling – which in some parts of the world is still used) the most accepted technique used today is stratigraphic excavation.
Stratigraphic excavation involves unearthing the various layers of a context (i.e. graves dug on top of one another) in the reverse order to which they where formed. To better explain this if you had one grave that had been dug next to another one and cut through the original when it was originally dug, you would excavate the later one by following the outline of the grave and then you would start excavating the original grave. In this way you can preserve the cut of the grave and this can often provide useful information which would otherwise be lost with other excavation methods.
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