I believe there was either another mutant with the ability to, or they found a way to, detect mutant abilities. I saw a short video that recapped the comics so I unfortunately don’t know a lot of the details. The name of the comic is linked on the wiki though.
The page doesn’t say how they figured out he had the power to do this. So- how did they figure out he had the power do to this?
He was already at Xavier’s school before he blew himself up.
I believe there was either another mutant with the ability to, or they found a way to, detect mutant abilities. I saw a short video that recapped the comics so I unfortunately don’t know a lot of the details. The name of the comic is linked on the wiki though.