Letter Bound for White House Tests Positive for Cyanide

WASHINGTON — A letter intended for the White House tested positive for cyanide at an off-site mail screening facility on Tuesday, according to a statement from the Secret Service.

The statement said the letter was received at the screening facility on Monday, and tested negative for biological agents. But officials said the letter returned a “presumptive positive for cyanide” on Tuesday and was transported to another site for further testing.

The statement did not say whether the letter was addressed to President Obama or to someone else at the White House. Officials also declined to say whether something specific had led them to test the letter.

“As this is an ongoing investigation, the Secret Service will have no additional comment,” the statement said.

In the weeks after the attacks of Sept. 11, 2001, a series of letters laced with anthrax were sent to members of the news media and public officials in the Washington area, including the White House and members of Congress, prompting weeks of anxiety. The anthrax killed five people and sickened 17 others, and officials eventually blamed a military scientist who later committed suicide.

As a result of those episodes, letters and packages destined for the White House are screened at remote locations to protect the president and his staff.

In 2013, federal agents arrested a man whom they suspected of sending letters laced with the poison ricin to Mr. Obama and a Republican senator. That case shook nerves in the capital and prompted the evacuation of some House and Senate office buildings.