Washington - It's traditionally highly effective against werewolves, witches, vampires and other monstrosities firearms experts warned today.
However the discovery of a sliver bullet inside security glass in President Obama's office has sent Security Service staff 'ballistic' as the hunt began for a lone drive-by shooter 'with attitude'.
"Of course we're not discounting theories it's a self-inflicted Halloween prank," FBI sources commented this morning, "the kind that might work miracles with Presidential popularity polls, heheh."
They have also strenuously denied that the initials 'B.O.' were carved on the bullet and reminded the public that the acronym for 'bodily odor' could easily be a message about personal hygiene of any of a number of White House employees.
Aides also at pains to point out that no shots had been heard in Constitution Avenue near the White House last Friday night and denied that an AK047 rifle was later discovered in an abandoned car close by.
Last year a 'Rahm Emanuel' vampire Halloween costume was discovered stuffed inside a White House freezer wrapped around a frozen dead duck.
Michelle Obama was unavailable for comment.