The watchdog's findings said Durham Police failed to properly scrutinise Atherton's 2006 application for a shotgun certificate and an application for a firearms licence two years later in 2008.

BBC: Durham PCC Ron Hogg calls for gun licence changes

The package also creates what lawmakers said is the nation's first statewide dangerous weapon offender registry, creates a new "ammunition eligibility certificate, " imposes immediate universal background checks for all firearms sales, and extends the state's assault weapons ban to 100 new types of firearms and requires that a weapon have only one of several features in order to be banned.

NPR: Conn. Lawmakers Unveil Bipartisan Gun Control Plan

To get the certificate, a buyer would need to be fingerprinted, take a firearms training course and undergo a national criminal background check and involuntary commitment or voluntary admission check.

NPR: Conn. Reaches Deal On Tough Gun Laws After Newtown