U.S. prosecutors have identified the Quebec woman suspected of mailing envelopes containing the poison ricin to the White House and law enforcement officials in Texas as Pascale Cecile Veronique Ferrier.
Ferrier, 53, is expected to appear in federal court in Buffalo, N.Y., today to face a charge of threatening U.S. President Donald Trump.
She was arrested at the U.S. border on Sunday and, according to the FBI, was in possession of a loaded gun at the time.
Officials in the U.S. say the letter sent to Washington, D.C., was intercepted at a mail sorting facility on Friday before it reached the White House.
The FBI believes Ferrier is linked to six letters also containing ricin that were sent to law enforcement officials in Texas last week.
The RCMP's Chemical, Biological, Radiological, Nuclear, Explosives team searched an apartment tied to the suspect in a Montreal suburb on Monday.