Oct. 3 (UPI) -- Authorities arrested a former Navy veteran from Utah for allegedly sending castor seeds to the White House, Pentagon and Sen. Ted Cruz, the U.S. Attorney's Office for Salt Lake City said Wednesday.
William Clyde Allen III, 39, was taken into custody after the suspicious mail containing castor seeds -- the source for ricin, a toxic poison -- was sent to government officials, U.S. attorney's office spokeswoman Melody Rydalch told the Military Times.
Allen served four years in the U.S. Navy and left in 2002.
One of the letters Allen is suspected of sending was addressed to President Donald Trump at the White House and two others were sent to the Pentagon. Those letters initially tested positive for the toxin ricin, authorities said Tuesday. Another letter was sent to Cruz's Houston campaign office and prompted an evacuation, but was later determined not to be hazardous.
"According to our preliminary analysis, the substance was castor seeds, from which ricin is derived. The FBI is still investigating," Pentagon spokeswoman Dana White said in a statement Wednesday afternoon.
The U.S. Secret Service said the letter to Trump didn't make it inside the White House, but the agency didn't say where it was intercepted.
"We are working jointly with our law enforcement partners to fully investigate this matter," the Secret Service said in a statement. "Further, all threats directed towards the president, or any Secret Service protectee, are treated seriously and fully investigated."
The Secret Service said the letter was found Monday.
Authorities said the letters were seized at a mail-sorting facility on the Pentagon campus, but away from the military headquarters building. The letters tested positive for ricin during what officials called an initial field test.
Also Tuesday, Cruz's campaign office in Houston received a letter that contained a "white powdery" substance.
Portions of the Phoenix Tower in Houston were evacuated. Tests later determined the substance wasn't hazardous.