Rabbit
The CIA, the FBI, and the LAPD all claimed to be the best at apprehending criminals. Finally they agreed on a test. A large forest was subdivided into three sections, and a rabbit was released into each one. THE MISSION: Catch the Rabbit
The CIA placed animal informants throughout their forest, and questioned all plant and mineral witnesses. After three months of exhaustive investigations they released a voluminous report documenting their conclusion: RABBITS DO NOT EXIST.
The FBI went into their forest, and - after two weeks with no leads - they burned the forest, killing everything in it (including the rabbit). They made NO apologies: The rabbit had it coming.
The LAPD went into their forest and emerged only two hours later with a badly beaten bear. The bear yelling: OKAY! OKAY! I'M A RABBIT!! I'M A RABBIT!!