The Secret Service says a letter sent to the White House this week has tested positive for cyanide, confirming an earlier report by The Intercept. According to that story, the letter's return address matches that of a man who previously mailed the White House "a package covered in urine and feces."

"On Monday 3/16/15, an envelope was received at the White House Mail Screening Facility. Initial Biological testing was negative; however, on 03/17/15, the chemical testing returned a presumptive positive for cyanide," said a Secret Service spokesperson in a statement to CNN. "The sample was transported to another facility to confirm the results."

A law enforcement alert reportedly states the listed sender has been known to the Secret Service since 1995. From The Intercept:

That person has sent multiple packages over the years, the most recent was received on June 12, 2012, which contained mini alcoholic beverages.

"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 alert states.

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