Many years ago I was an elder but was never involved in judicial committee duties. It sounds as if you were. My question to you: why wouldn't the committee want to interview her to see if his alibi, weak as it was, were true?
My only experience personally with how judicial committees work is as an elder's kid. But since leaving, I have done a lot of reading, and in the elder's handbook, it says that if a woman is charged with something and a judicial committee is formed, that the husband is to be informed and involved. But if a man is charged with something and a judicial committee is formed, then the elders are supposed to keep it confidential from the wife and just "encourage" the husband to tell her. Perhaps they did talk to her about his alibi, but in all those records, there is no mention of it, and there is nothing in the elder handbook that says they have to.