The proof is the physical male traits that are present on this person, its really as simple as that. No need for scientific tests really...!
There are heaps of info on this to research (physical differences between male and females) , such as - skull profile, length of arms, size of feet, ratio of ears, mouth on head, indentation to torso, hairline, etc...). If you google Sex Reassignment Surgery, there are heaps of places you can go to for this also.
As always, do your own homework and never believe everything you see or hear.