The Secret Service confirmed Thursday that a new ricin-laced letter was sent to President Barack Obama, the same week that two poisoned envelopes were sent to New York Mayor Michael Bloomberg.
The letter to the president is being investigated and tested by the FBI Joint Terrorism Task Force, according to Secret Service spokesman Edwin Donovan. Sources said the letter was intercepted at a mail screening facility and never reached the White House.
NBC News reported the letter made similar to threats as the one sent to Bloomberg and his gun control group, including the line: "What's in this letter is nothing compared to what I've got planned for you."
More from GlobalPost: Letters sent to Bloomberg tested positive for ricin
Two letters were sent to Bloomberg: one to his office in New York City on Friday and the other to his group Mayors Against Illegal Guns in Washington on Sunday.
In April, two letters laced with ricin, a poisonous toxin, were sent to the White House. A suspect, Matthew Ryan Buquet, was charged last week in connection with the incident.
Bloomberg said the threats would not affect his work on gun control.
"There's 12,000 people who are gonna get killed this year with guns and 19,000 that are gonna commit suicide with guns and we're not gonna walk away from these efforts," Bloomberg said.