A law enforcement official says a Texas home has been searched and a resident interviewed as part of the investigation into ricin-tainted letters sent to New York Mayor Michael Bloomberg, President Barack Obama, and Mayors Against Illegal Guns, a Bloomberg-affiliated gun control group in Washington, D.C.
Authorities blocked off the house in New Boston for hours Friday and set up tents in the yard while searching for evidence.
FBI agents entered the home wearing white hazardous materials suits and ventilation masks. New Boston is located near the Oklahoma and Arkansas borders.
Authorities were tipped off about the man after his wife noticed strange material in her refrigerator and searches for "ricin" on her computer.
ABC News obtained images of the letters. One of them reads: "You will have to kill me and my family before you get my guns.”
"Anyone wants to come to my house will be shot in the face. The right to bear arms is my constitutional God-given right and I will exercise that right 'til the day I die. What's in this letter is nothing compared to what I've got planned for you."
The letters never made it to Obama or Bloomberg.
The Associated Press contributed to this story.