porn accusations

So this week kicked off with a bomb being dropped on me. It was an unfounded accusation, and at the end of lots of investigation, we believe that our son is completely innocent. However, the days between Monday and Friday have been long and fraught with emotion.
I got an sms from a friend from school to say she'd like to have a chat about something. I said sure, when ? She said Monday after drop-off. Fine.
Monday morning we meet at the school gate, and start walking. She tells me she caught her son, the previous Thursday morning, looking at pornography on their iPad at home. He is in Zack's class.
When challenged, he declared that Zack had told him to look at the porn, and threatened to hit him if he didn't. And so she came to me...
Suffice it to say, we have looked at the search and browsing history on every device we own and their is NO evidence of visiting porn sites in the last few months. I don't believe that Zack is smart enough to hide his tracks yet. He struggles to log in to his profile sometimes, so I don't think he has the vaguest idea about deleting the browsing history or searching for cookies. If he had been up to something, we'd be able to find it with ease. Also, I know Zack, and he wears his heart on his sleeve. He wouldn't be able to cover up something like this.
In the end we decided not to raise it with Zack at all, as that would only make him want to know what his friend had done. Today Keith and I went back to the mum and said that we hadn't found anything, and that we don't believe that her son was telling the truth. We went further and asked why her son felt he should blame Zack?
This evening she made her son apologise to me. I was gracious and said, "it's OK". We need to leave it there really.

This is part of a much bigger issue in all directions. For starters, Zack has become the scapegoat in alot of stuff that happens at school - both in the classroom and on the playground.

What a week!....
(more to follow)