Ricin reportedly sent to White House in mail

WASHINGTON — Letters sent in recent days to the White House and to local law enforcement agencies in Texas contained the lethal substance ricin, and investigators are trying to determine whether other envelopes with the toxin were sent through the postal system, a law enforcement official briefed on the matter said Saturday.

Investigators believe that the letters were sent from Canada and have identified a woman as a suspect, the official said. The letter to the White House, which was addressed to President Donald Trump, was intercepted, as were the letters to a detention facility and a sheriff’s office in Texas.

The envelope to the White House was caught at the final off-site processing facility where mail is screened before being sent to the White House mailroom, according to a second law enforcement official. The Postal Service irradiates mail that is addressed to the White House and other federal agencies in the Washington area, and the mail is sorted in a facility that samples the air for suspicious substances.

The Joint Terrorism Task Force in Washington is leading the investigation, with assistance from New York, according to multiple law enforcement officials. So far, investigators have found no links between the ricin letters and any international terrorist groups, but the investigation is in its early stages, and nothing has yet been ruled out, one senior official said.

Ricin, which is part of the waste produced when castor oil is made, has no known antidote.

‘‘The FBI and our U.S. Secret Service and U.S. Postal Inspection Service partners are investigating a suspicious letter received at a U.S. government mail facility,’’ the FBI said in a statement. ‘‘At this time, there is no known threat to public safety.’’