On Monday, Canadian police searched a house in the Montreal area in connection with a letter directed to US President Donald Trump that was suspected of containing the toxin ricin.
The operation, which took place at the request of the FBI, came after a suspected woman was arrested trying to cross from the United States to Canada, according to a source in the Royal Canadian Mounted Police.
The woman, who was carrying a firearm when she was arrested, is due to appear in a US court on Tuesday to face federal charges.
A special unit of the Royal Canadian Mounted Police, which includes experts in biological and nuclear threats and explosives, searched a house in Langley, south of Montreal.
Police refused to clarify whether the home belonged to the suspect, and revealed that letters containing ricin were sent to five other addresses in Texas.
Police in Hidalgo County, Texas, reported that envelopes containing ricin were sent to four police officers, without directly referring to the case of the letter sent to the White House.
“At the moment, I cannot make further statements because there is an ongoing federal investigation” of the case, Eddie Guerra, Hidalgo Police Officer, said on Twitter.
The Canadian media identified the suspect as Pascal Freire, 53, who holds Canadian and French citizenship.
Ricin, which is produced by processing castor beans, is fatal even if it is ingested, inhaled, or injected in a very small dose, as it causes organ failure.
Trump’s message was discovered last week before it reached the White House, according to what “The New York Times” and “CNN” reported.
Letters to the White House are usually scanned and arranged in warehouses outside Washington.
CNN reported that the contents of the envelope were repeatedly checked in a warehouse to ensure that it contained ricin.