Sometimes, they know they have the wrong guy. Sometimes, it doesn’t seem to deter them.
I give the terrible case of Reynaldo Cruz.
Formulation not formula. A formula would, presumably, be based on math. For example, by taking into the account the hardship endured by the innocent who were wrongly jailed and the greater harm caused by the guilty who went free, and arriving at a best compromise ratio. If you further take into account the probability that a person convicted of a crime, regardless of his guilt for that particular crime, may have genuinely been a criminal, I doubt that a computed ratio for the overall best compromise would be 10:1.
Which is, of course, nonsensical. Think about it: If they didn’t all sound similar, then the prosecutors would have jumped on that. How can the alibis be true if they’re inconsistent? And just what does it mean for them to sound “rehearsed”? Did they rehearse it so well that they managed to make it sound just like the truth? Must be lies, then.
Not necessarily…
The “best” testimony would clearly be in each person’s own words, but describing the same event. (Like in elementary school, when you’re asked to define terms using your own words. Everyone should have the right answer, but they should all be different enough.)
So, for example, if they all saw him swimming at the YMCA, you’d expect someone would say “the pool” others would say “the gym” while others might say “the Y.” If the they all say, verbatim “He was swimming at the YMCA” then that’s when it starts sounding rehearsed.
Or it can also sound rehearsed if everyone has all the same details. If he got some soda from the refrigerator and every witness says they remember it being a 12 oz can of diet Pepsi, that seems unlikely. Surely some people only remember it was “a drink” or “a soda.” Most of the time, most of us are not paying enough attention to know too many specifics.