Washington, Sept 20(UNI) US officials said on Sunday that they intercepted an envelope which was addressed to the White House and was found to be containing a substance identified as ricin, a deadly poison.
The package was intercepted "earlier this week", according to a CNN report citing law enforcement officials.
CNN further reported that tests carried out on the envelope identified the lethal substance.
According to reports letters were sent "in recent days" to the White House and to federal agencies in the US state of Texas.
Investigators believe that the package was sent from Canada and have identified a woman as a suspect reports said.
Investigators are trying to ascertain as to whether more such envelopes have been mailed.
Ricin is a poison found in castor beans, the US Centers for Disease Control and Prevention says on its website, and there is no antidote for the deadly substance.
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