Okay, this could be a lengthy process.
@carbuff asked if you've checked prisons. Each state has it's own system, too. Decades ago I worked for my state government in Child Support Enforcement -- if someone has been in prison, there are records.
I started with Texas, here:
https://inmate.tdcj.texas.gov/InmateSearch/start
Oddly enough, there is no Steven Murphy, that's a fairly common name & the Texas Department of Justice is big. We'd often start there, just because there was a huge number of inmates.
Illinois offers a sort of one-stop-shopping:
www2.illinois.gov
Now Illinois has 2 inmates named Steven Murphy, both are African-American. Didn't check the other options.
California has no one listed:
CDCR Public Inmate Locator Disclaimer
I searched for last name Murphy, first name just ste as there are at least 2 ways to spell Steven/Stephen.
Type (name of state) inmate search, generally will have a .gov address.
Just something to try, the AWOL story indicates Mr. Murphy may have had some legal trouble?
Did you find a divorce decree? Was that by publication? Those documents may have information new to you.
jmho ymmv lrr