Is an alibi that is unconfirmed the same as one that is false?
I am not sure what you mean Antonia, but if you cannot confirm an alibi by the townie, you CANNOT assume that it is real OR fake.
You will have to eliminate the suspect in other ways.
A "none of your buisness" is the same as someone lying about their alibi.
If you can not confirm the alibi because you can not get the Townie to talk to you about it, then that is all you know. They could be a liar or telling the truth.