I haven’t read about the scientists and their reports of this case.
Typically, they have no explanation.
They note the lack of blood and that we have no capacity to drain blood that thoroughly from anything.
They note the precision of the cuts and that at least until lasers, we could not do that. Some say even our lasers cannot do exactly the same thing.
Sometimes they will offer something equivalent to
—swamp gas, weather balloons, venus
levels of explanation but none of them ever hold water and when the scientists are with those they trust, they say that they have no explanation.