You are grossly overestimating the governments of the worlds ability to co-operate and you seem to have an understanding of the brain interfacing technology that's mostly based on sci-fi.

The problem with "mind scanning" is that it would quite likely only be able to vaguely guess at what you were thinking of at the exact given moment you were being "scanned", making it extremely unreliable.
Alternatively if it by means of voodoo magic can perfectly analyze every facet of the human mind as if it were a computer file, they'd quickly run into the problem of having to either kill or sterilize a fifth or more of the male population.

The technology in the second case would require a perfect understanding of every facet the entirety of the human brain, something that I don't think we'll manage to achieve any time soon if at all.
The technology in the first case is less reliable than penile plethysmography, albeit with less false positives and more false negatives.

Not only is the technology in this hypothetical scenario of yours completely improbable and utterly impractical, to assume that all the governments of the world would simultaneously be able to co-operate with each other on something as huge as this when most of them can't even agree with themselves is totally absurd.

Furthermore, I gravely doubt that normal folk would just sit back and let the government rummage through their brains unopposed just to hunt some half imagined boogieman. For that to happen the entire world would have to turn into 1984 overnight and the very concept of human rights would have to be erased from existence.

Short version: Tech doesn't work that way and neither do governments.