Where do you find mugshots of past inmates?
If you know the inmate's name, then enter it here http://goo.gl/q1uMFK , generally, the more you know about the inmate, the better.
You can visit a site which allows you to specify the names, city and country of the inmate you would want to search for. Consider http://www.lookuppeople.net. The site is helpful as it has photos for easy identification.