This is a list of incidents involving the poison ricin. The incidents are predominantly attempts to use the poison for attacks, rather than accidents and non-criminal events.

1970s September 1978, London, UK, assassination of Georgi Markov On September 7, 1978, Bulgarian dissident Georgi Markov was jabbed in the leg in public on Waterloo Bridge, London by a man using a weapon built into an umbrella which fired a small pellet carrying ricin into Markov's leg. Markov died four days later.Andrew, Christopher M.; Mitrokhin, Vasili (2000). The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB . Basic Books. p. 334. . Retrieved November 29, 2012.

1980s August 1981, Vienna, Virginia, US, assassination attempt on Boris Korczak On August 14, 1981, CIA agent Boris Korczak, who had infiltrated the KGB but had been exposed, was shot like Georgi Markov with some sort of weapon that fired a minuscule pellet containing a potentially lethal dose of ricin into his kidney while he was shopping at Giant Food Store in Vienna, Virginia. Korczak and the CIA are convinced that this assassination attempt was the work of the KGB, as he had penetrated it deeply and harmed it significantly. Korczak survived, which he attributes to being shot in the kidney, causing his body to expel the projectile as though it were a kidney stone before it could kill him.Carus, W. Seth (2002). Bioterrorism and Biocrimes: The Illicit Use of Biological Agents Since 1900. Fredonia Books (NL). p. 81. (Center for Counterproliferation Research and National Defense University). Retrieved November 29, 2012.

1990s December 1995, Onia, Arkansas, US In April 1993, Thomas Lavy was caught while trying to smuggle 130 grams of ricin from Alaska into Canada. Lavy stated that he purchased the ricin to poison coyotes on his farm in Arkansas and keep them away from his chickens. Lavy was stopped at the Beaver Creek border crossing by Canadian custom agents who found, along with the 130 grams of ricin, $89,000, a knife, four guns, and 20,000 rounds of ammunition.

January 1997, Janesville, Wisconsin, US Authorities discovered various toxic substances in the house of Thomas Leahy in Janesville, Wisconsin. They discovered the substances after they had been called to Leahy's home after he had shot his son in the face, following a night of drinking. Among the chemicals discovered were 0.67 grams of ricin and nicotine mixed with a solvent that allowed it to penetrate the skin and have lethal effects. Authorities also found books relating to the production of chemical and biological agents. Chemicals were also found in a storage shed that Leahy kept in Harvard, Illinois. He reportedly told his sister that he was going to use the poison to coat razor blades and mail them to his enemies in hopes that they would cut themselves and be exposed. Leahy pleaded guilty to possession of the ricin and was sentenced to eight years for the shooting and six-and-one-half years for possessing dangerous materials.Ostrander, Kathleen (April 29, 1997). "Man Faces Charge o Toxin Possession". Milwaukee Journal Sentinel. p. 5.Murphy, Kevin (May 2, 1997). "Judge Orders Man Held for Toxin". Milwaukee Journal Sentinel. p. 5.Lederberg, Joshua (ed.); Cohen, William S. (1999). Biological Weapons: Limiting the Threat . MIT Press. p. 299. . Retrieved November 29, 2012.

April 1997, James Dalton Bell The US Internal Revenue Service (IRS) investigators searched the home of James Dalton Bell, a 39-year-old electronics engineer, and discovered a cache of chemicals, which included sodium cyanide (500 grams), diisopropyl fluorophosphate, and a range of corrosive acids. Subsequent analysis of computer files confiscated from the residence revealed that Bell engaged in e-mail communications with a friend, Robert East, a 46-year-old merchant marine radio operator, that expressed a desire to obtain castor beans to see if they could extract ricin. Bell had already acquired the home addresses of nearly 100 federal employees from the Federal Bureau of Investigation (FBI), IRS, and Bureau of Alcohol, Tobacco and Firearms, and computer files from voter registration. Bell was in the process of producing and acquiring chemical and biological agents.Painter, Jr., John (May 20, 1997) "IRS Says Suspect Discussed Sabotage". Oregonian. p. P-1

March 1998, Michigan, US Three members of a splinter group of the North American Militia in Michigan were arrested on weapons and conspiracy charges. The April 1998 indictment was the result of an investigation involving an Alcohol, Tobacco, and Firearms (ATF) agent who infiltrated the group in March 1997. When federal law enforcement raided the homes of these men, they discovered an arsenal of weapons and a videotape. Produced in a cooking-show format, the tape gave instructions on how to manufacture bombs and other assorted militia-type weaponry, including a feature segment on how to extract ricin from castor beans. During the court proceedings, prosecutors drew attention to the ricin segment, stating that the men were "collecting information on the manufacture and use of ricin." However, other than the videotape, no materials associated with ricin production were found in any of the raids.Singhania, Lisa (June 2, 1998) "Militia member admits his role in bomb plot". (Associated Press), Detroit News.

November 1999, Tampa, Florida, US Press reports indicated that FBI agents had apprehended a man in Tampa, Florida, for threatening to kill court officials and "wage biological warfare" in Jefferson County, Colorado. James Kenneth Gluck, 53, a former Colorado resident, sent a 10-page letter to Jefferson County judges threatening to kill them with a biological agent. He specifically identified one judge by name. FBI agents arrested Gluck on 5 November 1999 as he left a public library near his home in Tampa. Police, fire, and hazardous materials (HazMat) crews responded to the scene along with the FBI and blocked off Gluck's street. Upon searching his residence the next day, agents discovered that Gluck had the necessary ingredients to make ricin, though no refined ricin was actually found. They also found test tubes and beakers, as well as a copy of The Anarchist Cookbook and books on biological toxicology, in a makeshift laboratory in his home.

2000s August 2001, Russia and Chechnya The Russian Federal Security Service told the Itar-Tass news service it had intercepted a recorded conversation between two Chechen field commanders in which they discussed using homemade poisons against Russian troops. According to Itar-Tass, Chechen Brigadier General Rizvan Chitigov asked Chechen field commander Hizir Alhazurov, who is now living in the United Arab Emirates, for instructions on the "homemade production of poison" for use against Russian soldiers. Russian authorities reportedly raided Chitigov's home and seized materials, including instructions on how to use toxic agents to contaminate consumer goods, a small chemical laboratory, three homemade explosives, two land mines, and 30 grenades. The confiscated papers reportedly also contained instructions on how to produce ricin from castor beans.

June 2002, Spokane Valley, Washington, US Kenneth R. Olsen, 48, was arrested for possession of the biological agent ricin in his Spokane Valley office cubicle. Co-workers at Agilent, a high-tech company, tipped FBI officials about the software engineer after discovering documents on "how to kill", undetectable poisons, and bomb-making Olsen had printed out from his computer. Olsen insisted that his research was for a Boy Scout project, but did not say more. Further investigation of his office produced test tubes, castor beans, glass jars, and approximately 1 gram of ricin. In July 2003 Olsen was convicted of possessing a chemical weapon and possessing a biological weapon. He was sentenced to 165 months, almost 14 years in prison. Bill Morlin, "Ricin maker sentenced", The Spokesman Review, October 29, 2003

August 2002, Ansar al-Islam Reports emerged that Ansar al-Islam, a Sunni militant group, was involved in testing poisons and chemicals including ricin. According to one report the group tested ricin powder as an aerosol on animals such as donkeys and chickens and perhaps even an unwitting human subject. No more specific details were released.Bale, Ph.D., Jeffrey M.; Bhattacharjee, Anjali; Croddy, Eric; Pilch, MD, Richard (February 29, 2008). "Ricin Found in London: An al-Qa'ida Connection?" . cns.miis.edu. Center for Nonproliferation Studies, Chemical and Biological Weapons Nonproliferation Program. Retrieved November 30, 2012.

January 2003 arrests in the UK

On 5 January 2003 the Metropolitan Police raided a flat in north London and arrested six Algerian men who they claimed were manufacturing ricin as part of a plot for a poison attack on the London Underground. No ricin was recovered as a result of this raid. Only one person was convicted (of conspiracy to cause a public nuisance by the use of poisons and/or explosives to cause disruption, fear or injury) and jailed for 17 years. He had previously received a life sentence for stabbing and killing a policeman during the raid.

The U.S. Secretary of State Colin Powell used this incident in his 5th February 2003 speech to the UN as part of the case for the 2003 Invasion of Iraq, as the "UK poison cell" part of the alleged Abu Musab al-Zarqawi global terrorist network.

2003 letters in the US

In 2003, a package and letter sealed in a "ricin-contaminated" envelope was intercepted in Greenville, South Carolina, at a United States Postal Service processing center."Investigation of a Ricin-Containing Envelope at a Postal Facility - South Carolina, 2003" . Morbidity and Mortality Weekly Report. Centers for Disease Control. November 20, 2003.

Ricin was detected in the mail at the White House in Washington, D.C., in November 2003. The letter containing it was intercepted at a mail handling facility off the grounds of the White House, and it never reached its intended destination. The letter contained a fine powdery substance that later tested positive for ricin. Investigators said it was low potency and was not considered a health risk. This information was not made public for nearly three months, when preliminary tests showed the presence of ricin in an office mailroom of U.S. Senate Majority Leader Bill Frist's office. There were no signs that anyone who was near the contaminated area developed any medical problems. Several Senate office buildings were closed as a precaution.

April 2004, Kirkland, Washington, U.S. In April 2004, Kirkland, Washington resident Robert M. Alberg was arrested by FBI for possession of ricin. Alberg, son of businessman Tom Alberg, has Asperger’s syndrome and was diagnosed with clinical depression: federal prosecutors stated that they did not believe that he had political motivations for making the poison and had no plans to use it. In June 2005, Alberg was arrested for violating the conditions of his parole by possessing castor bean seeds; he was sentenced to three years in a federal prison.

January 2006, Richmond, Virginia, US In January 2006, ricin was found in a home in suburban Richmond, Virginia, in the form of mashed castor beans. The suspect, Chetanand Sewraz, was allegedly isolating the toxin to kill his estranged wife.

February 2008, Las Vegas, Nevada, US