In an appearance on CNN's "State of the Union," Hickenlooper pointed to the Aurora movie theater shooting that left 12 people dead and 58 others wounded.
There has been speculation that the suspected shooter, James Holmes, will change his not guilty plea -- entered by a Colorado judge -- to not guilty by reason of insanity, The Denver Post reported.
"After the shootings last summer in the movie theater, we really focused on mental health first then universal background checks," Hickenlooper said referring to why the three bills he signed into law Wednesday did not ban semi-assault weapons.
Colorado has "some of the best elk hunting, deer hunting, I mean, it's a state where we have a long tradition of a relationship with guns and hunting and that traditional approach from father to child," he said. "So, you know, we tried to look at if we wanted to tighten up a little bit things like universal background checks which clearly make a significant difference, that's where we put our initial focus."