"On Monday March 16, an envelope was received at the White House Mail Screening Facility. Initial Biological testing was negative; however, on March 17, the chemical testing returned a presumptive positive for cyanide," Secret Service spokesman Brian Leary said in a statement on Tuesday.

"The sample was transported to another facility to confirm the results," a statement said.
    
The envelope listed a return address for a man who has a record with the Secret Service dating back to 1995, which includes sending a package covered in urine and feces, according to online publication 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," the website said.