Two Detectives

A crime was committed in Puzzleton, and 8 possible suspects were identified. Working separately, two detectives (Albert and Brutus) each narrowed down the list to two names. They know that between them, they have three names on their lists and the name that is shared is the actual culprit.

The two detectives meet at the police station to compare notes and find out who the final suspect is, but they are not allowed to communicate unless a police officer is with them. How can they each learn who the culprit is without the police officer knowing? (The officer may know the culprit is one of two people, but should not have definite knowledge at the end of their conversation.)

Can a method be found if there were originally more or less than 8 names?

[How do they know they share a single name on their two lists? Why don't they meet somewhere other than the police station? Why can't the police officer be trusted? Why do the detectives' names conveniently begin with the first two letters of the alphabet? This is Puzzleton, where certain things just are, and should not be questioned... -KD]

Source: Bert Sevenhant, citing Vladomir Mascharouk, from White Russia (Belarus).

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