Secret Service: Letter sent to White House tests tentatively for cyanide.
An envelope received by the White House mail screening facility tested positive for cyanide, the Secret Service confirmed. The envelope received Monday initially tested negative but returned a presumptive positive for cyanide Tuesday, according to a Secret Service. The sample was taken to another facility to confirm the results.
The envelope containing a milky substance was in a container wrapped in a plastic bag, according to an internal law enforcement document obtained by The Intercept.