A Texas man was being questioned by federal agents on Thursday night in connection with the ricen-laced letters sent to Mayor Michael Bloomberg.
The man's wife contacted the FBI when she found a container with what looks like ricin in the refrigerator, The New York Post reports.
She also found instructions on "how to make ricin" in their home, sources told the Post.
The man, who resides in the town of New Boston, is being described as an Army veteran who does contract work for the Department of Defense, according to NBC.
New Boston is approximately 100 miles from Shreveport, La. where letters were sent out on May 20. The letters tested positive for ricin and contained a message that is similar to a message sent to President Barack Obama this week.
Officials emphasized that the man is not considered a suspect at this time and that they are still in the early stages of the investigation.
Metro's original story is below.
A ricin-laced letter sent to President Barack Obama appears to be similar to letters sent to Mayor Michael Bloomberg, according to a source briefed on the matter.
The letter was intercepted before reaching the president, the Secret Service said in a statement to POLITICO.
According to NBC News, the text of the letter to the president was identical to the letters sent to Bloomberg, including the line "what's in this letter is nothing compared to what I've got planned for you."
Last week, letters were sent to Bloomberg and his gun control advocacy organization, Mayors Against Illegal Guns. According to POLITICO, both letters referenced the "debate on gun laws."
The FBI office in New York confirmed that they are investigating the letter sent to Mayor Bloomberg.
Follow Danielle Tcholakian on Twitter @danielleiat