You have to ask yourself, if you were in the employer's shoes, what would make you feel comfortable hiring this guy? Most employers want to see a pattern of stable work history and solid references. If you can show that your life has been together for the last 12 years since that incident when you were 17, I don't think it will automatically disqualify you. As long as you're truthful and I'm assuming you will be, any concerns they have will be addressed by the psychological evaluation.
"We enjoy freedom and the rule of law on which it depends, not because we deserve it, but because others before us put their lives on the line to defend it."
- Thomas Sowell