A computer-obsessed man ordered enough deadly poison on the Dark Web to kill 1,400 people then set about finding a rabbit, chinchilla or other "pocket-sized pet" to test it on, a court heard.
Father-of-two Mohammed Ali, 31, from Liverpool, allegedly tried to buy 500 mg of ricin worth 500 US dollars (£322) from a dealer in the United States who went by the names of Dark Mart and Psychochem.
But the software programmer was unaware that the man he had been communicating with on the Internet black market was in fact an undercover FBI agent known as Peter who alerted British police.
Under the username Weiros 0000, Ali first approached Dark Mart in January with a private message: "Hi, would you be able to make me some ricin and send it to the UK?"
In a series of encrypted chats they went on to discuss details including the price of a lethal dose, discounts for bulk orders and repeat purchases, and ricin's "shelf life", jurors were told.
At one point Ali asked: "How do I test this ricin?" and received the instruction: "You must test it on a rodent."
On February 10, Ali took delivery of a toy car with "special batteries" at the home he shared with his wife and two young sons.
The five concealed packets did not contain ricin but a harmless powder and the toy was covered in a "unique marker" which sticks to skin on contact and can be seen under a UV light, the court heard.
When police swooped to arrest Ali they seized the opened package from his home office as well as his computer and mobile phone.
The computer showed that Ali had begun searching Google in October last year for poisons such as abrin, ricin, and cyanide.
On February 4, records showed he had made a payment of 2.1849 Bitcoins, the online currency, jurors were told.
Meanwhile, he had made a list on his computer which included the entries "paid ricin guy" and "get pet to murder".
After receiving the delivery, Ali searched Google for "pocket sized pets", "animal rescue centre", "chinchillas Liverpool" and "rabbit rehome - adopt an unwanted bunny from a rescue centre", the jury was told.
Ali's mobile phone also showed Google and Yahoo searches for "How to make ricin" and "what poison kills you quick, is foolproof, easily found/made, easily concealed and hard to detect post mortem".
Prosecutor Sally Howes QC told jurors that ricin was "the poisoner's perfect poison" because its symptoms are non specific and it does not show up in a post mortem.
A 100 mg dose is enough to kill up to 280 people within three to five days if ingested or injected while 500 mg can kill between 700 and 1,400 people, she said.
Ali, who is originally from Bolton, denies the charge of attempting to possess a chemical weapon between January 10 and February 12 this year.
Ms Howes said he is likely to argue that he sought to buy ricin on the Dark Web "out of curiosity" and his attempt to possess it was for "peaceful purposes" and not to use it as a chemical weapon.
She said his defence team was likely to rely on a psychological assessment that Ali has traits associated with Asperger's syndrome to explain what he did.
The Old Bailey trial is expected to go on for two weeks.