A person of interest has been identified in the investigation of ricin-laced letters sent to President Barack Obama and New York City Mayor Michael Bloomberg. He’s described as a Texas resident who searched for “ricin” on his home computer and apparently was keeping the toxic substance in his refrigerator.

The person of interest, whose name has not been publicly released, is from New Boston, Texas, according to CBS News. Authorities searched his home as part of the investigation into the letters tainted with ricin sent to Bloomberg. The letter sent to Obama was deemed suspicious and is being tested for the toxic and potentially deadly substance.

The Texas man’s wife became suspicious of his activities and notified authorities when she smelled a strange odor coming from her refrigerator, sources told ABC News. She also saw computer searches for ricin on their computer. 

The person of interest was questioned by the FBI in Texarkana, Texas.

Both letters sent to Bloomberg -- one handled by a mail sorting facility in Manhattan and another addressed to his gun control advocacy group, Mayors Against Illegal Guns -- tested positive for ricin, while the Obama letter is being tested by the FBI for the deadly poison. Neither Bloomberg nor Obama came in contact with the missives.

The three letters contained identical wording:

"You will have to kill me and my family before you get my guns," the letter reads. "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 postal service union said in a memo to employees that the Bloomberg letters were postmarked in Shreveport, La. That location services mail from Louisiana, Arkansas and Texas. It was later revealed that the Obama letter was also postmarked in Shreveport.

News about a person of interest in the ricin letters case came as yet another similar missive sent to Obama was intercepted, according to the FBI. The fourth letter was mailed from Spokane, Wash., the Seattle FBI field office said in a statement.

While the FBI publicly announced the letter’s interception on Thursday, the action was actually taken May 22.

That same day, the FBI arrested 38-year-old Matthew Ryan Buquet for allegedly sending a ricin-laced letter to a Spokane federal judge. He was charged with mailing threatening communications, a federal offense that can carry stiff penalties.

Five suspicious letters, including the ones sent to Obama and the judge, were seized, the FBI said. Other letters detected for ricin in Spokane included missives sent to the CIA, a Spokane post office and Fairchild Air Force Base.

The U.S. Attorney’s Office in Spokane declined to comment on whether the Spokane letters are connected to the Bloomberg and Obama messages.

“The United States Attorney’s Office for the Eastern District of Washington is fully engaged in this matter and has made no comment on whether additional charges may be sought in connection with the continuing FBI and U.S. Postal Inspection Service [USPIS] investigation,” the FBI said.

Obama hasn’t commented publicly on the letters, but Bloomberg said his gun control efforts would not be deterred by the threatening missives.

“In terms of why they’ve done it, I don’t know,” Bloomberg said. “The letter obviously referred to our anti-gun efforts. But there’s 12,000 people who are going to get killed this year with guns and 19,000 that are going to commit suicide with guns, and we’re not going to walk away from these efforts.”