Doctor on trial for alleged poisoning attempt using chemical weapon ricin on mother's partner, court hears

Dr Thomas Kwan, 53, denies charges of attempted murder and causing grievous bodily harm with intent but has admitted to administering poison to Patrick O'Hara.

Prosecutor Peter Makepeace KC told Newcastle Crown Court that police discovered a range of dangerous chemicals, including arsenic and liquid mercury, in Kwan's garage in Ingleby Barwick, Teesside, following his arrest. Among the items found were castor oil beans and coffee filters, along with a recipe for making ricin, a highly toxic poison classified as a chemical weapon.

“Recovered from Mr Kwan’s office, in the house itself, was a recipe for manufacturing ricin from castor beans, using filtration," Makepeace told the court. "Ricin, many of you will know, is a highly toxic poison and a scheduled chemical weapon.”

Makepeace explained that while Kwan refused to answer questions related to the alleged poisoning of Mr O’Hara during police interviews, he did provide details about the chemicals found in his garage. Kwan informed officers that the chemicals were safe if left sealed and advised them not to open any of the containers.

The prosecution highlighted that medical professionals working to treat Mr O’Hara, who had developed necrotising fasciitis, needed to know which poison had been used. The discovery of castor oil beans and the ricin recipe raised concerns that ricin could have been the toxin injected.

However, Professor Steven Emmett, Chief Medical Officer at the Defence Science and Technology Laboratories, reviewed the case and concluded that ricin was unlikely to have been used. He suggested instead that the chemical iodomethane, often used in pesticides, was the likely poison.

Further investigation revealed that Kwan had searched the term "iodomethane" on his phone 97 times leading up to the incident. According to Makepeace, “If you want to not only inject a substance that causes necrotising fasciitis into a person but make it as difficult as possible for the medical team to identify the cause and treat the illness, iodomethane is the one to pick.”

In addition to the chemicals, police searches of Kwan's computer uncovered a range of incriminating materials, including a PDF on police murder investigations, a video on how to produce iodomethane, an eBook titled Forensic Science and Medicine: Criminal Poisoning, and The Terrorist’s Handbook.

The court also heard that Kwan had installed spyware on his mother’s computer, allowing him to monitor her emails and watch her and Mr O’Hara through the laptop’s camera. He also used his surgery as a front to order chemicals from legitimate suppliers, the prosecution said.

The trial continues.