Firearm suicide and homicide rates associated with level of background check / Eurekalert.org, 3 June 2008
http://www.eurekalert.org/pub_releases/2008-06/mcow-fsa060308.php
"States that perform local-level background checks for firearms purchases are more effective in reducing firearm suicide and homicide rates than states that rely only on a federal-level background check, according to a new study by researchers at the Medical College of Wisconsin in Milwaukee"