Bloomberg Targeted in Failed Ricin Mail Poisoning, Police Say

WASHINGTON, D.C. May 29, 2013 — -- New York City Mayor Michael Bloomberg is the latest high-profile target of poison-tainted letters sent through the mail, police revealed today.

The leader of the nation's largest city was threatened anonymously in two letters sent to Bloomberg's offices in Manhattan and Washington, D.C., NYPD spokesperson Paul Browne said. An undisclosed number of New York cops who responded to one of the letters now "are being examined for minor symptoms of ricin exposure," but the potentially dangerous substance never reached the mayor.

"The writer, in the letters, threatened Mayor Bloomberg, with references to the debate on gun laws," Browne said.

In addition to Bloomberg, another letter was sent to the director of the Mayors Against Illegal Guns in D.C. Browne said preliminary tests on that letter showed it also appeared to contain ricin, though the Washington police report of the incident said that "no hazmat (hazardous) material was found."

Bloomberg, a billionaire who has long crusaded for stricter gun control around the country, responded with a flash of defiance.

"No, I do not feel threatened," the mayor told reporters tonight. "This was not the first letter that was sent to anybody. In terms of why they did it - I don't know - the letter referred to our anti-gun efforts. There are 12,000 [people] that are going to be killed this year with guns and 19,000 are going to commit suicide by guns and we are not going to walk away from those efforts."

"I speak for close to 1,000 mayors in the effort against gun violence. This is a scourge against the country and we need to make sure to get this under control," he added.

Asked if he was angry, Bloomberg said he wasn't.

"There are people that do things that might appear irrational - things that are wrong," he said. "But it's a complex world out there. And you just have to deal with that."

At its most dangerous ricin can kill, though it is quite difficult to deliver a dose that intense. The poison, which comes from castor beans, stops cells from synthesizing proteins so victims can suffer organ failure.

Ricin is relatively easy to make with recipe instructions available online. Experts do caution that people trying to concoct the toxin on their own risk poisoning themselves.

MORE INFO: Facts About Ricin From CDC.gov

Officials declined to discuss the toxicity levels of the Bloomberg letters, and they declined to reveal the text of the mail. An official briefed on the probe told ABC News that in each letter "the text is identical" and the letters were postmarked in Louisiana.

Last month, ricin-tainted letters were sent to President Obama and to government offices, including that of Sen. Roger Wicker, R-Miss.

The letter addressed to the president was received at the White House mail facility and included the message "To see a wrong and not expose it is to become a silent partner to its continuance."

READ: Ricin Letters Suspect Expected to Appear in Court

The Senate mail facility received the letter addressed to Wicker. It contained the same message.

A ranking counter-terrorism official in New York marveled at how ricin has become so popular among those trying to scare of harm others more than 11 years after anthrax-tainted mail terrified a nation still reeling from the 9/11 attacks.

"Instead of the drug of choice, it [ricin] has become the weapon of choice of people who might be thinking that," the official said.