Minecraft…catch xray user?

Hosting hamachi server with 4 people, we are playing survival, but this one guy is knows for using hacks in games which we dont approve, and we think he is using x-ray mod.

All of the indications are there that he has it, in 4 hours of gameplay he had 50+ diamonds, and his mines are not linear but alot of curves, ups and downs like he is chasing them diamonds.

Well i would tell him to gtfo, but he is best friend of my good friend and we dont want any "accusations" because we cant prove that he does not have x-ray because he is type of spoiled arogant asshole that will never addmit it, and accuse us for not beliving him… You know the type.

So, im asking is there some way i can catch him in act?
Like some anti-cheat that i can isntall on my server so that he gets banned, or any other way i can be 1000% sure he is using it?

Thank you.

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