Threatening letter sent to White House found shortly after others meant for Bloomberg were found to have traces of ricin
The secret service said on Thursday that a suspicious letter addressed to President Barack Obama similar to the ones sent to New York mayor Michael Bloomberg was intercepted by a White House mail-screening facility.
The letter has been turned over to the FBI's joint terrorism task force for testing and investigation.
It was unclear how the letter, intercepted on Wednesday by the White House facility, was similar to the ricin-laced ones addressed to Bloomberg.
Two threatening letters postmarked in Louisiana and containing traces of the deadly poison ricin were sent to Bloomberg in New York and to his gun-control group in Washington, officials said.
The anonymous letters were opened in New York on Friday at the city's mail facility in Manhattan and in Washington on Sunday at an office used by Mayors Against Illegal Guns, the nonprofit started by Bloomberg, police said Wednesday.
New York police spokesman Paul Browne said preliminary testing indicted the presence of ricin in both letters but that more testing would be done. He said the threats contained references to the debate on gun laws and an oily pinkish-orange substance.
The postal workers' union, citing information it got in a US postal service briefing, said the letters bore a Shreveport, Louisiana, postmark.
Louisiana state police spokeswoman Julie Lewis said state authorities have deferred to the FBI and have not opened an investigation. The Shreveport postal center handles mail from Louisiana, Texas and Arkansas, so the letter might have come from any of those states, Lewis said.
The mayor didn't respond to questions about the letters Thursday morning as he arrived for and left a speech to the Real Estate Board of New York.
The billionaire mayor has emerged as one of the most potent US gun-control advocates, able to press his case with both his public position and his private money.
The people who initially came into contact with the letters showed no symptoms of exposure to the poison, but three officers who later examined the New York letter experienced minor symptoms that have since abated, police said.
Last month, authorities in Washington intercepted a letter addressed to Obama that contained a "suspicious substance". This letter was similar to one mailed to Mississippi Republican senator Roger Wicker, which tested positive for ricin.