Bergendorff, 57, kept four grams of ricin, which is enough to kill hundreds of people, in his motel room in February, the Las Vegas Review-Journal reported.

Although the prosecution and defense agreed to a 37 months sentence for Bergendorff, the judge gave him more prison time because of the severity of the crime.

Bergendorff called emergency personnel Feb. 14 after complaining of having breathing difficulty. Two weeks after he was admitted to a hospital, hotel staff entered his motel room and discovered a .22-caliber Browning pistol and a .22-caliber Ruger rifle, both with silencers attached.

Police searched the room and found the ricin, the newspaper reported.

"Used improperly, ricin can be a very dangerous and deadly weapon," U.S. Attorney Gregory Brower said after the hearing. "As this case demonstrates, the U.S. Department of Justice will prosecute anyone found to be unlawfully in possession of such toxins."

Assistant U.S. Attorney Gregory Damm said in April Bergendorff possessed enough of the chemical agent to kill more than 500 people.