This is an follow-up to Alibi by Recording. Discussing that post on Twitter made me think of a more modern version of using a recording to convince someone that the murderer is in a place when he’s actually somewhere else committing the murder.

Instead of merely recording a conversation which would be overheard, the murderer could record a series of responses and use voice recognition to map a tree of responses to what a microphone hears. Thus the murderer could actually have a conversation with someone—through a locked door. Something like this:

Janice: [knocks] Are you working late again?

Bob: Yes. I have to get these reports done for tomorrow.

Janice: Can I get you some coffee?

Bob: No thanks, I already got myself some coffee. In the big mug. It’s going to be a late night.

Janice: OK, I’ll leave you to it.

Bob: Good night.

Janice would swear to the police that she had a conversation with Bob while Bob was really off murdering his Aunt for the inheritance she was leaving him. Since these sorts of programs can have a history, it could eventually go to some default response like “I’m sorry but I have to concentrate on work. I’ll talk to you in the morning.”

Not foolproof, of course, but that most interesting murders are at least a little bit daring.

I still think that this would be a completely unsatisfying reveal to a modern audience. And yet it would be very directly analogous to, say, the murderer of Roger Ackroyd using a phonograph of the deceased to convince people that the deceased was alive when he was already dead (as happened in the Poirot story, The Murder of Roger Ackroyd).

And I maintain, as I did in my previous post on the subject, that it’s because a technological solution is simply not very interesting. We’ve got technology up the wazoo and back out again, these days. What we find very interesting is the human element.