https://www.businessinsider.com/ricin-poison-letter-sent-to-trump-woman-is-the-suspect-2020-9
An envelope posted to the White House containing the lethal substance ricin was intercepted by US authorities on Saturday.
The letter addressed to President Donald Trump appears to have been sent from Canada, and officials have identified a woman as a suspect, according to a report by the New York Times.
It was stopped at the final off-site government mail center before it arrived at the White House.
"The FBI and our US Secret Service and US Postal Inspection Service partners are investigating a suspicious letter received at a US government mail facility," the FBI said in a statement, according to Times. "At this time, there is no known threat to public safety."
Similar envelopes were sent to law enforcement agencies in Texas, including a detention facility and a sheriff's office.
The Joint Terrorism Task Force in Washington is taking charge of the investigation with help from New York and the Royal Canadian Mounted Police (RCMP).
No links have been found between the poisonous letter and any international terrorist organizations, investigators said. They declined to elaborate on what evidence they had that pointed them to the female suspect.
However, officials have said that the investigation is still in its early stages, and nothing has yet been ruled out.