Usually when answer gets deleted directly (i.e. not as side effect of its parent question deleted) it says "deleted by [name here] [time stamp]". Plus, it always leave a revision.
However, I just stumbled over this answer on Stack Overflow:
Finally, the last straw... revisions of the deleted answer itself:
Another thought was maybe some automagical conversion to comment, but no such comment exists.
Can anyone shed some light over this phenomenon?