Envelope containing ricin addressed to White House may have been sent from Canada: RCMP A spokesperson for the FBI said the police force has arrested “an individual allegedly responsible for sending a suspicious letter.”The news comes a day after the RCMP confirmed it received a request from the FBI to assist with the investigation into the letter.According to the RCMP, FBI analysis of the envelope indicated the presence of ricin, a potentially lethal poison derived from castor beans.“Initial information from the investigation suggests that the letter originated in Canada,” an RCMP spokesperson said in a statement Saturday.The envelope was intercepted at a government facility that screens mail addressed to the White House and the U.S.