Letter Sent to Mayor Bloomberg Tests Positive For Ricin

Writer referenced gun laws

A letter addressed to Mayor Michael R. Bloomberg that arrived late last week at a municipal building has tested positive for ricin, according to two people familiar with the matter.

A second letter containing the poison arrived at a building in Washington that houses Mayors Against Illegal Guns, a group Mr. Bloomberg helps run and finances, a person familiar with the matter said. Investigators believe both letters were sent by the same person.

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