Secret Service Initial Tests Finds Cyanide On Envelope Posted To White House

The U.S. Secret Service has found out after two rounds of testing that a letter sent to the White House contains traces of the chemical cyanide.

In an internal memo obtained by The Intercept, Secret Service officials said on Monday that initial biological testing for the letter tested negative, but a second chemical analysis returned a "presumptive positive" on Tuesday. Officials say the letter has been sent to another unspecified facility for further testing.

"An envelope containing an unknown milky substance, in a container wrapped in a plastic bag, received at the White House Mail Screening Facility, tested positive for Cyanide," the memo says.