Irrelevant Conclusion

If an arguer argues for a certain conclusion while falsely believing or suggesting that a different conclusion is established, one for which the first conclusion is irrelevant, then the arguer commits the fallacy of irrelevant conclusion.
Example:

In court, Thompson testifies that the defendant is a honorable person, who wouldn't harm a flea. The defense attorney rises to say that Thompson's testimony shows his client was not near the murder scene.

The testimony of Thompson may be relevant to a request for leniency, but it is irrelevant to any claim about the defendant not being near the murder scene.