"Well this person shouldn't have had any kind of weapons and bombs and other devices and it was illegal for him to have many of those things already," Romney said. "But he had them. And so we can sometimes hope that just changing the law will make all bad things go away. It won't. Changing the heart of the American people may well be what's essential, to improve the lots of the American people."
The guns used in the attacks were purchased legally between May 22 and July 6 at three Colorado gun stores, according to officials. "We're told the weapons he used were legal. And the ammunition he purchased over the internet was not prohibited," reports CBS News' Bob Orr.
The bombs and other explosive devices set as booby traps in alleged shooter James Holmes' apartment appear not to have been legal, but they were not used in the initial attack and did not cause fatalities.
(Romney called for unity following the shooting in Aurora, Colo., last week.)
The comment marks Romney's second statement on the tragedy, in which 12 people were killed and 58 injured. On Monday, he told CNBC that he did not believe stricter gun laws could have averted this type of tragedy.
"There are - were, of course, very stringent laws which existed in Aurora, Colorado," said Romney, who signed into law an assault weapons ban as Massachusetts governor in 2004.
What constitutes "stringent" is open to interpretation. But it appears that Holmes had a relatively easy time legally obtaining the assault weapon, other guns and ammunition he allegedly used in the murders. Guns do not need to be registered in Colorado, they can be carried openly without a permit, and government and law enforcement are barred from building a database of gun owners.
In addition, International Business Times reports, Aurora could not have strengthened its gun laws even if it wanted to. Under state law, Aurora and other municipalities are explicitly prohibited from enacting "an ordinance, regulation or other law that prohibits the sale, purchase or possession of a firearm that a person may lawfully sell, purchase or possess under state or federal law."