Dear Precious
It's very important for the future for you to be able to trust each other. Would going behind his back to check his criminal record help build that trust?
Perhaps it's better to spend time getting to know him, his family and friends. You don't say whether you life close to each other and have been able to spend a lot of time together.
Another thing you could do is some marriage preparation. In your case some thing like FOCCUS or Prepare would be ideal - they help you to explore what your views are about things, and the values you share. You can find out more
here and
here.
Liz