One thing that I can tell you, is that there's no way to apply "one size fits all" templates to them all. Some will shine like you wouldn't believe, if given the chance, and some would, at best, be crappy employees. I doubt there would be a problem with workplace violence, with most, but it's entirely possible that you could end up with a "dud."
In short, each case needs to be handled on an individual basis, with careful, extensive human interaction. Lots of "tell me a story" interviews. Coding tests are likely to be useless.
Since that kind of employee search seems to be a thing of the past, in our industry, it can be tough for these folks to get in the door. This woman went to bat for her friend. There's not a whole lot of folks willing to do that.
BTW: The US is horrible for that kind of thing. Even a small misdemeanor can be a scarlet letter for life. I knew a guy that was busted in [an Ivy-League] college for pot (a misdemeanor), and pursued a career in banking. Even a quarter-century later, that bust followed him, and stunted his chances (he was real good).
One of the most intelligent people I ever met (and I have met a lot of really smart people) was a violent felon that went away at 17, and was profoundly twisted by the experience. He was never able to readjust properly. That marvelous intellect was never able to benefit us.