An envelope containing ricin poison was sent to the White House, US media outlets reported, citing law enforcement.
A woman arrested by US authorities on suspicion of sending a ricin-filled envelope to the White House was due to appear before a federal court in Buffalo, New York, on Tuesday.
The Department of Justice said Pascale Cecile Veronique Ferrier, 53, is charged with making threats against the president of the United States.
The envelope was intercepted at a government mail centre before it arrived at the White House, Canadian police said on Saturday.
Canadian police on Monday searched an apartment in a Montreal suburb linked to the suspect. She has joint Canadian and French citizenship, two sources told Reuters News Agency.
According to the charging documents released on Tuesday, Ferrier included a message to President Donald Trump in the envelope.
“I found a new name for you: ‘The Ugly Tyrant Clown.’ I hope you like it,” she wrote. “You ruin USA and lead them to disaster.”
Ferrier referred to the poison in the envelope as a “special gift,” adding that if it did not work, she might find a “better recipe for another poison” or resort to using a gun.
“Enjoy! FREE REBEL SPIRIT,” she wrote.
US authorities arrested Ferrier on the Canada-US border on Sunday, at the so-called “Peace Bridge” that runs between Fort Erie, Ontario, and Buffalo.
She was due to make her initial appearance before US District Judge H Kenneth Schroeder Jr at 4pm EDT (20:00 GMT).
The woman is suspected of sending a total of six letters, with the other five addressed to law enforcement and detention facilities in South Texas, a US law enforcement source told Reuters.
So far, no links to political or terrorist groups have been found but the investigation is continuing, the source said.
The police department in Mission, Texas, received a suspicious letter within the last week, Art Flores, a spokesman for the department, said on Monday. The department did not open the envelope and turned it over to the FBI, he said.
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Flores said police in Mission had arrested Ferrier in 2019.
The five other letters “contained similar language” to the letter that was sent to Trump and were sent to people affiliated with facilities where Ferrier had been jailed in 2019.
Investigators also matched Ferrier’s fingerprints from four of the letters, the complaint said.
Ricin can cause death within 36 to 72 hours from exposure to an amount as small as a pinhead. No known antidote exists to reverse its toxic effects.