Not sure what that means in relationship to your previous post.
IOW, you don't know if they have committed any crimes, and you don't know anything about them.
No, we don't know a person's criminal history, or lack of one when they arrive if they aren't documented. We are pretty good at keeping up with that after they get here though, and the numbers just don't show that is the expected outcome. Yes, again, some of them are purely evil, and no, I don't think it is OK to allow even a few bad people in, but as a whole it's unreasonable to assume they are all unacceptable. Instead of a stupid wall that will never work, we need a reasonable immigration policy. The way it is now, a person who is a direct relative of a citizen has to wait as much as 5 to 10 years, and spend a fortune. A reasonable immigration policy would work. The crap being put forward now won't.