An envelope addressed to President Donald Trump was intercepted on Tuesday after it was suspected to contain ricin and appeared to be connected to similar envelopes sent to the Pentagon.
In addition to the letter being addressed to Trump, two envelopes were delivered to a mail facility outside the Pentagon and initially tested for ricin, a U.S. defense official told CNN.
"The Secret Service can confirm receipt of a suspicious envelope addressed to the President on Oct. 1, 2018," a Secret Service spokesman said. "The envelope was not received at the White House, nor did it ever enter the White House."
A source familiar with the ongoing joint federal investigation said that based on preliminary investigative activity, the White House and Pentagon letters were believed to be connected and the substance in question was a very crude castor bean concoction that authorities were not technically calling "ricin" until further testing.
Ricin is a highly toxic compound extracted from castor beans that has been used in terror plots. It can be used in powder, pellet, mist or acid form. If ingested, it causes nausea, vomiting and internal bleeding of the stomach and intestines, followed by failure of the liver, spleen and kidneys, and death by collapse of the circulatory system.
The two suspicious envelopes sent to the Pentagon were addressed to Secretary of Defense James Mattis and to chief of naval operations, Adm. John Richardson, the official told CNN.
The mail facility is in a separate building on the grounds of the Pentagon, and the two pieces of mail that tested positive never entered the Pentagon building.
Pentagon spokesperson Col. Rob Manning said that all U.S. Postal Service mail sent to the Pentagon mail screening facility on Monday was being quarantined and no Pentagon personnel were in danger.
"On Monday, the Pentagon Force Protection Agency detected a suspicious substance during mail screening at the Pentagon's remote screening facility," Manning said in a statement. "The envelopes were taken by the FBI this morning for further analysis."
The FBI also issued a statement earlier that they had possessed the two envelopes that were suspected of containing ricin and were doing more testing.
"On Tuesday, October, 2, 2018, in coordination with the Pentagon Force Protection Agency, FBI Special Agents took possession of two suspicious envelopes that had been screened at the Pentagon mail facility. Those envelopes are currently undergoing further testing. As this is ongoing, we will have no further comment," the statement read.