Secret Service officials say the letter tested positive for the poison ricin and was from the same sender who mailed the letter to Sen. Roger Wicker (R-Miss.) that also tested positive, NBC News reports. Federal officials told NBC News that they believe they know who sent the letters, but no arrest has been made.
From the Hill:
The Secret Service has acknowledged the letter addressed to President Obama contained a suspicious substance but has not stated it was ricin, a deadly poison.
On Tuesday, lawmakers revealed that a letter addressed to Sen. Roger Wicker (R-Miss.) had tested positive for the poison.
The Secret Service said the letter was sent to Obama on April 16 and was discovered at a remove White House mail screening facility.