Lakhvir Kaur Singh, a British woman of Indian descent, was married to Aunkar Singh and had three children. Her husband was undergoing cancer treatment during the time leading up to the crime. Singh engaged in a clandestine 16-year affair with Lakhvinder "Lucky" Cheema, which began in 1993. The affair persisted even after Cheema moved out of Singh's residence. Singh's relationship with Cheema was marked by emotional volatility, and she reportedly became pregnant twice during the affair, with both pregnancies ending in abortion.

In November 2008, Cheema ended his long-standing affair with Singh and became engaged to 21-year-old Gurjeet Choongh. Singh, unable to accept the end of the relationship, traveled to India and obtained a toxic substance known as bikh, derived from the Aconitum ferox plant. On January 27, 2009, Singh visited Cheema's home in Southall, West London, and laced a leftover chicken curry in his refrigerator with the poison. That evening, Cheema and Choongh consumed the curry. Cheema suffered severe symptoms, including vomiting, numbness, and paralysis, and died shortly after arriving at the hospital. Choongh experienced similar symptoms but survived after being placed in a medically induced coma. ​

During the investigation, a lodger testified to seeing Singh tamper with the curry. Additionally, a plastic bag containing brown powder was found in Singh's coat pocket, which she claimed was medication for a rash but was identified as Indian aconite.

Singh was arrested on January 28, 2009, and charged with murder and grievous bodily harm. During her trial at the Old Bailey, she attempted to blame her brother-in-law for the poisoning, but the evidence against her was overwhelming. On February 10, 2010, Singh was convicted of murdering Cheema and causing grievous bodily harm to Choongh. She was sentenced to life imprisonment with a minimum term of 23 years. ​