Deadly threats will not prevent New York City Mayor Michael Bloomberg from pursuing tighter gun laws, the outspoken gun control advocate said Thursday after anonymous letters addressed to him tested positive for ricin.

“The letter was obviously referring to our anti-gun efforts, but there’s 12,000 people who are going to get killed this year with guns,” Bloomberg said. “We’re not going to walk away from those efforts.”

U.S. Secret Service also confirmed on Thursday that the White House mail screening facility intercepted a separate letter addressed to the White House that was similar to the letters previously addressed to Bloomberg…

Tests conducted on Wednesday confirmed two anonymous threatening letters sent to Bloomberg and Mark Glaze, director of Mayors Against Illegal Guns, contained the presence of ricin. The poison, which can be a white powder or orange liquid, is found naturally in castor beans. It can be fatal for up to 72 hours.

“What’s in this letter is nothing compared to what I’ve got planned for you,” the anonymous person wrote in the letter sent to Bloomberg. “You’ll have to kill me and my family before you get my guns…blah, blah, blah!

Law enforcement sources said the letters were postmarked May 20 from Shreveport, La.

The letter to Bloomberg was opened on Sunday and the letter to Glaze was opened on Friday. Bloomberg’s letter was intercepted at a mail sorting facility in Manhattan, and Glaze’s letter was encountered at Washington, D.C., offices. Everyone who came into contact with the letters was unharmed.

“I’m not angry. There are people who I would argue do things that may be irrational, do things that are wrong,” Bloomberg said. “But it’s a very complex world out there, and we just have to deal with that.”

Bloomberg is way too forgiving. I don’t mind laying a bit of understanding on the woefully ignorant who populate, say, the Tea Party or line up at the American Legion bar on Friday night to tell war stories. But, the criminal arrogance of cowards who fear democracy so much they resort to attempted murder deserve no sympathy.

Lock ’em up and throw away the key.