Can u please tell me if this proves something?

For my history ignment we're doing a mock trial of the ination of John F. Kennedy & we also have to bring a piece of physical evidence & we are all igned a different character. My character is a police officer who saw the in, Lee Harvey Oswald, on the 2nd floor of the building which JFK got shot just 90 seconds after the assassination. My character is trying to say that it couldn't have been Oswald, he wouldn't have enough time to get down to the 2nd floor from the 6th floor(where he shot JFK) within 90 seconds. I was thinking of bringing a sketched map of the second floor & point out where he & my character were on the 2nd floor at that time, but does it kind of prove that Oswald couldn't have been the killer? I'm really confused & sorry its long but do u think the map may prove something? It may not be true historically, but that's what my character believes. Thanx anyways!