I say that is cr@p.<quoted text>I think most seasoned detectives might admit that the immediate witness accounts...right after the incident, are the most accurate.
And I'll point to twenty years of TV "true crime dramas" (20/20, 48 Hours, etc) where the witnesses are brought in for an interview and they tell a story... and then the detectives pull out evidence (security camera, data stamps, cell phone records) and the witness statements change.
This "John" DID NOT and could not have seen what he told the detectives initially.
It very well may be he did not "lie" about what he saw- he allowed himself some "importance" in what happened and ... "embellished" what he claimed to have seen.
HE WAS INSIDE THE BUILDING ON THE PHONE AND HEARD THE GUNSHOT.