A person holds seeds of the castor oil plant containing the deadly poison ricin on June 14, 2018, in Berlin. (Credit: Jens Kalaene / AFP / Getty Images)

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A La Crescenta man pleaded guilty Monday to trying to buy ricin from an undercover FBI agent with plans to use the potent and deadly poison as a weapon, federal prosecutors said.

Steve S. Kim, 41, admitted to violating a criminal statute prohibiting biological weapons after reaching a plea agreement with prosecutors, the U.S. Attorney’s Office for the Central District of California said in a news release.

Last year, Kim spent two months trying to get ricin from what he thought was an online seller, but was actually an FBI operative, officials said.

Kim told the agent he planned to use the poison on someone weighing 110 pounds, and said he would pay 320 Euros — about $350 — in bitcoin, according to the plea agreement.

FBI agents even pretended to ship the ricin, and delivered another substance in a concealed package to Kim’s L.A. workplace on Nov. 29, 2018. Kim was arrested immediately after taking the parcel home that evening and accessing the fake poison, prosecutors said.

“Ricin is an incredibly dangerous biological toxin — just a few tiny grains can kill a human,” U.S. Attorney Nick Hanna said in a statement. “Because it can be used as a weapon of mass destruction and there is no antidote for ricin poisoning, any attempt to acquire this deadly chemical agent is an extremely serious matter that will prompt a vigorous response.”

The defendant is scheduled to be sentenced Nov. 18, when he’ll face a maximum possible sentence of life in federal prison. But the government has agreed to recommend a sentence of no more than 87 months in prison as part of the plea deal, prosecutors said.