Correct me if I'm wrong, but I believe we have had several discussions about what grandson AH may have been doing on the day he disappeared. Mom's said he is a computer genius, some clever people have told me the kind of work she's referencing could be defined as 'a bunch of blokes with screwdrivers, laying cables'.
Taking a point halfway between the two, I'm guessing if he was working, he was on a computer somewhere. If he was working alongside people, he will have been easily able to verify that to LE.
If he was on his own, however.....well, I just found it interesting that on another thread, a project manager for IBM who worked from home and part of whose alibi was that he was working on the computer when his wife disappeared; has been charged with her murder. Part of the evidence LE have said they have, is that he wasn't working on his computer when he said he was.
Forensic computer people are good. They live in a strange, twisty online world though, where strange symbols and figures and trails pop up and lead to strange places. It's all too much for me. I'd get halfway and make a big mistake.
But it looks like some of the people who lay those false trails in the first place can make big mistakes too.