For the third time in two months, letters tainted with the poison ricin have been intercepted on the way to a public figure. In this case, letters addressed to New York City Mayor Michael Bloomberg arrived last week at both a Manhattan municipal building and the Washington, D.C., office of Mayors Against Illegal Guns, an organization Bloomberg finances and helps lead.

"The writer, in letters, threatened Mayor Bloomberg, with references to the debate on gun laws," Paul J. Browne, chief spokesman for the NYPD, told the New York Times.

This year's previous ricin scares took place in Mississippi and Washington state. Suspects have been arrested in both of those cases.

[Image via AP]