The arid climate of Jerusalem would provide good conditions to stop decomposition. The dry and cool tomb would’ve kept Jesus’ body from decomposing rapidly. At the very least, the body would’ve contained the same basic structure of Jesus, including his hair, his wounds, and basic physical features.
We have no document that states a body was exhumed. Instead, we have multiple lines of evidence for the empty tomb (see “Empty Tomb”). In fact, no early Christians needed to respond to this assertion—even though they responded to other claims from skeptics (see Celsus, Trypho, etc.).