An NRI woman from Punjab is being questioned in London over a suspected double cyanide poisoning that left her former boyfriend dead and his young fiancee fighting for her life.
The couple, 39-year-old Lakhvinder Cheema and 21-year-old Gurjeeta Kaur, were admitted to the West Middlesex Hospital in the early hours on Wednesday.
According to the police, the two had taken seriously ill after eating food at their home in Feltham. Cheema was pronounced dead at 2.36 am, while Kaur was described as critical on Thursday night.
Police were called in after the hospital became suspicious about the nature of the couple's illness and suspected a case of cyanide poisoning.
Lakhver Kaur, who is in her forties, has been arrested and was being questioned in connection with the case. A 54-year-old man is also in custody after being arrested on Thursday in Windsor.
Cheema is said to have worked for a pest control company and detectives have taken away his work kit to see whether poisons from it had been used. Officers also removed samples of food from the couple's home for tests.
There were reports that officials initially feared the death could have been caused by an airborne biological or radiological attack and a full emergency alert was launched.
Police said they are treating the death as "highly suspicious". A postmortem on Cheema was being carried out.
A Scotland Yard spokesman said: "The suggestion that the victims might have been poisoned is one of the lines of inquiry that we are currently pursuing." Cheema's three-bedroom house was cordoned off last night with a police van parked outside. Neighbours said he had recently proposed to Gurjeeta.