There must be news that the document has been modified
Would count as Defacement
Paint on the doc
writing anything on the doc with a specific POV
carving bad words or selfish graffiti or a political message or symbol into it
If the "nominal" original constitution were defaced but there were heavy unofficial rumors that this wasn't the "real" constitution. Unless they were confirmed, if it's officially the real one, it's the real one
Some gov't group modifies it physically, then is pursued and considered illegal, and also the change they made is invalidated and officially not considered binding or validly part of the document
Would not count as Defacement
splattering paint on case
carving up the backup copy's non-original case
paint on backup copy
writing "I support this" on the original constitution
document destroyed or lost
Some US govt group which retroactively is in control (1 yr later) manages to legally (according to themselves) modify the document, such as an amendment, or special affirmation of some slogan (added by the CIA secretly, but legally according to them, and they are not then known as an illegal organization)
The point is whether the doc itself is modified not so much on identifying the person/people/group who does it.